Top Republicans responded Tuesday to the Trump administration’s hard-line immigration policy of separating families at the U.S.-Mexico border, a “zero tolerance” policy implemented six weeks ago. Many Republicans responded publicly to the harsh criticism over the policy, saying they support keeping migrant children and parents together.

Update 11:07 p.m. EDT June 19: Trump administration officials have been sending babies and other young children forcibly separated from their parents at the U.S.-Mexico border to at least three "tender age" shelters in South Texas, according to The Associated Press.

Lawyers and medical providers who have visited the Rio Grande Valley shelters described play rooms of crying preschool-age children in crisis. The government also plans to open a fourth shelter to house hundreds of young migrant children in Houston, where city leaders denounced the move Tuesday.

The three centers -- in Combes, Raymondville and Brownsville -- have been rapidly repurposed to serve needs of children including some under 5. A fourth, planned for Houston, would house up to 240 children in a warehouse previously used for people displaced by Hurricane Harvey, Mayor Sylvester Turner said.

Update 10:00 p.m. EDT June 19: The growing backlash against the Trump administration's immigration policy is expanding as tech workers take a stand in Silicon Valley.

Microsoft workers are demanding the tech giant end its relationship with Immigration and Customs Enforcement in the wake of the forced separation of families at the U.S. southern border.

Some 100 Microsoft employees signed an open letter that calls for the company to sever its ties with ICE, according to The New York Times.

“We believe that Microsoft must take an ethical stand, and put children and families above profits,” employees said in the letter.

The letter was addressed to Microsoft chief executive, Satya Nadella.

Microsoft has a contract with ICE worth more than $19 million "for processing data and artificial intelligence," the Times reported.

Axios reported the letter demanded three things: Cancel its contract with ICE, create a public policy stating that "neither Microsoft nor its contractors will work with clients who violate international human rights law," and commit to "transparency and review regarding contracts between Microsoft and government agencies, in the US and beyond."

Update 8:30 p.m. EDT June 19: Protests unfolded in several U.S. cities Tuesday against the Trump administration's "zero tolerance" immigration policy, which has resulted in the separation of at least 2,000 children from their parents at the U.S.-Mexico border over the past six weeks.

In New York, opponents of the policy marched from Union Square to Lower Manhattan, demanding an end to the separation policy.

In San Francisco, protesters marched to the Immigration and Customs Enforcement building, demanding that the agency stop separating children from their parents at the border.

Protesters also gathered in Philadelphia’s Rittenhouse Square to protest the administration’s immigration policy during an appearance by Vice President Mike Pence at a GOP fundraiser.

Update 6:30 p.m. EDT June 19: As President Donald Trump meets with Congressional Republicans this hour over immigration, it's unclear whether lawmakers can agree on immigration legislation and whether the meeting will address the controversial policy of separating undocumented families at the U.S. border.

Trump is reportedly urging House Republicans to pass “the compromise bill and the Goodlatte bill,” according to The Hill, which is citing GOP sources.

Senior Trump administration officials are doubling down on the administration's "zero tolerance" immigration policy, calling out opponents of the plan, according to a new statement, the Huff Post reported on Twitter.

“The administration’s zero tolerance policy is a response to a humanitarian crisis brought about by loopholes in federal immigration law that encourage human trafficking and smuggling. As a result of these loopholes, the only two options for the U.S. government are to either release into the country illegally all illegal Central American migrants who show up at our border with a minor, or to prosecute them for illegal entry. There is no policy of family separation,” the statement said.

“The Trump administration has repeatedly asked Congress to give us the authority to detain families together and promptly return families together. Members of Congress who are pushing to give immunity for child smuggling will only increase the crisis ten-fold.”

The statement urges Congress to close the loopholes so the government can return “illegal alien families in a fair, expeditious and humane fashion.”

Update 4:42 p.m. EDT June 19: An undocumented child with Down syndrome was separated from her parents while illegally trying to cross the U.S.-Mexico border, according to The Wall Street Journal.

The 10-year-old girl was separated from her parents, even though her father is a legal U.S. resident, and sent to an immigration facility in McAllen, Texas, the Journal reported, while her mother was sent to a facility in Brownsville. The separation occurred while the mother was trying to get the girl and her brother across the border.

The newspaper learned of the situation after an interview with Mexico's Foreign Prime Minister Luis Videgaray.

During a speech at a small business event Tuesday, Trump blamed Mexico for contributing to the crisis at the U.S. southern border, saying the Mexican government could help end the stream of people traveling to the U.S. if it wanted to.

Update 3:09 p.m. EDT June 19: Senate Majority Leader Mitch McConnell, R-Kentucky, said Tuesday that Republicans support creating a plan to keep migrant children and parents together amid criticism of a Trump administration policy that separates families suspected of coming into the country illegally at the border.

“I … and all of the other senators of the Republican conference support a plan that keeps families together,” McConnell told reporters Tuesday.

Sen. Orin Hatch, R-Utah, has passed a letter around to colleagues calling on U.S. Attorney General Jeff Sessions to stop separating families, The Hill reported.

“I’m asking for a pause,” Hatch said. “I think we ought to pause and look at this very carefully.”

Update 2:07 p.m. EDT June 19: A pair of Florida Democrats was barred Tuesday from going inside a Miami-area facility housing immigrant children as the national debate raged around the Trump administration's policy of separating migrant children from parents at the border.

U.S. Rep. Debbie Wassermn Schultz and U.S. Sen. Bill Nelson attempted to enter the Homestead Temporary Shelter for Unaccompanied Children Tuesday, but Wasserman Schultz said they were told that they needed to put in a request to visit the facility two weeks ahead of time.

The lawmakers said that they were told by the company that runs the facility that they would be able to visit Tuesday, but they were stopped by the a representative of the U.S. Department of Health and Human Services.

“This is not a good day for our country, where a U.S. senator and a U.S. congressman have been turned away from a federal facility because the Trump administration does not want us to check on the welfare and the care of the children inside -- children who have been taken from their moms and dads,” Nelson said.

Update 1:30 p.m. EDT June 19: President Donald Trump once again blamed laws passed by Democrats for his administration's policy of separating migrant children from parents suspected of coming into the country illegally while speaking Tuesday at a meeting of the National Federation of Independent Business.

Trump said the policy is necessary because loopholes in the immigration laws mean families “cannot  be detained together or removed together, only released.”

“These are crippling loopholes that cause family separations,” Trump said. “Child smugglers exploit the loopholes and they gain illegal entry into the United States, putting countless children in danger.”

There is no law that mandates the separation of children and parents at the border.

“We've got to stop the separation of the families, but politically correct or not we have a country that needs safety, that needs security, that has to be protected,” Trump said. “We don’t want people pouring into our country, we want them to come in through the process, through the legal system and we want ultimately a merit-based system where people come in based on merit.”

Update 11:40 a.m. EDT June 19: More than 20 state attorneys general are calling for an end to the Trump administration's immigration policy, which has led to children being separated from their parents at the border and has sparked national outrage.

The 21 Democratic state attorneys general, from states including Massachusetts, North Carolina, Pennsylvania and Washington, sent a letter Tuesday to U.S. Attorney General Jeff Sessions and Homeland Security Secretary Kirstjen Nielsen.

“Put simply, the deliberate separation of children and their parents who seek lawful asylum in America is wrong,” the attorneys general said in the letter. “This practice is contrary to American values and must be stopped. We demand that you immediately reverse these harmful policies in the best interests of the children and families affected.”

The group is led by New Mexico Attorney General Hector Balderas, who on Tuesday called the immigration policy “inhumane” and “draconian.”

“The Justice Department is ignoring its legal and moral obligations for the sake of a political agenda at the expense of children and the efforts of state law enforcement officials,” Balderas said. “The latest move to unnecessarily separate families is cruel and another example of this administration putting politics ahead of people.”

Update 10:15 a.m. EDT June 19: President Donald Trump insisted on Twitter that "Democrats are the problem" in the immigration debate as criticism of his administration's policy of separating children from parents at the border continues.

Trump wrote Tuesday morning that Democrats “don’t care about crime and want illegal immigrants, no matter how bad they may be, to pour into and infest our Country, like MS-13.”

The president has blamed Democrats for the recent surge in family separations, saying that laws need to be changed in order to change the separation policy.

“Now is the best opportunity ever for Congress to change the ridiculous and obsolete laws on immigration,” Trump said Tuesday in a tweet with the hashtag #CHANGETHELAWS.

There are no laws mandating the separation of children and parents at the border.

The president also wrote Tuesday morning that “if you don’t have Borders, you don’t have a Country,” and reiterated a claim that crime has risen in Germany since the country started accepting migrants, despite government numbers that show crime at its lowest rate since 1992.

Update 9:44 a.m. EDT June 19: The executive director of the United Nations Children's Fund called stories of children being separated from their parents as a result of the Trump administration's immigration policy "heartbreaking," saying in a statement Monday that "such practices are in no one's best interests, least of all the children who suffer their effects."

“Detention and family separation are traumatic experiences that can leave children more vulnerable to exploitation and abuse and can create toxic stress which, as multiple studies have shown, can impact children’s long-term development,” said Henrietta Fore, an American who has headed UNICEF since earlier this year.

She noted that the U.S. government has long supported UNICEF’s efforts to help uprooted children in Syria, South Sudan, Somalia and Haiti.

“Children -- no matter where they come from or what their migration status -- are children first and foremost,” she said. “I hope that the best interests of refugee and migrant children will be paramount in the application of U.S. asylum procedures and laws.”

Update 8:40 a.m. EDT June 19: Sen. John McCain called the Trump administration's family separation policy "an affront to the decency of the American people" in a tweet Monday night.

The Arizona Republican said the policy is “contrary to principles and values upon which our nation was founded.”

“The administration has the power to rescind this policy,” he wrote. “It should do so now.”

McCain is among a growing number of Republican lawmakers voicing concern over the administration's "zero tolerance" approach to illegal border crossings. Under the policy, all unlawful crossings are referred for prosecution. With adults detained and facing prosecution, any minors accompanying them are taken away.

Nearly 2,000 children were separated from their families over a six-week period in April and May.

Update 7:15 p.m. EDT June 18: The nonprofit news organization ProPublica released an eight minute audio recording of wailing children, who were separated from their parents last week.

A U.S. border patrol agent can be heard laughing in the background as the 10 children from Central America are separated from their families.

Update 6:00 p.m. EDT June 18: Homeland Security Secretary Kirstjen Nielsen, during a briefing Monday afternoon, said there's nothing new about the current policy of separating undocumented children from their parents at the U.S.-Mexico border.

"This entire crisis is not new, Nielsen said, pointing to "loopholes" in federal immigration laws from the past, but that could change this week with the introduction of several immigration measures in the U.S. House and Senate, including one from Texas Sen. Ted Cruz.

Cruz is expected to introduce the “Protect Kids and Parents Act,” according to news reports. The measure would double the number of federal immigration judges from 375 to 750. It would authorize new temporary shelters to better accommodate families.

The bill would mandate that immigrant families remain together, unless there’s criminal conduct or a threat to the children, and it would require that asylum cases are heard within 14 days of application.

Update 5:35 p.m. EDT June 18:  The head of the Department of Homeland Security, Kirstjen Nielsen, addressed the growing backlash over the Trump administration's zero-tolerance immigration policy at the southern U.S. border, which is separating undocumented children from their parents. Nielsen defended the policy and urged

Congress to fix the system and close the loopholes.

Update 5:30 p.m. EDT June 18: Two more first ladies have weighed in on the widening controversy over the Trump administration's policy of separating children from their parents at the southern U.S. border. Michelle Obama retweeted comments Laura Bush made that Trump's "zero-tolerance policy is cruel. It is immoral. And it breaks my heart."

Former first lady Rosalynn Carter also released a statement Monday, according to The New York Times. "The practice and policy today of removing children from their parents' care at our border with Mexico is disgraceful and a shame to our country," Carter said.

Update 4:30 p.m. EDT June 18: The Department of Health and Human Services has released photos of the "tent city" in the Texas border outpost of Tornillo, just outside of El Paso, where the U.S. government is sending children separated from their parents at the border. There are already dozens of children at the facility, according to news reports.

Update 3:10 p.m. EDT June 18: Sen. Kamala Harris, D-California, called Monday for the resignation of Department of Homeland Security Secretary Kirstjen Nielsen amid the ongoing debate over the Trump administration's immigration policy.

The demand came one day after Nielsen said in a tweet that, “We do not have a policy of separating families at the border. Period.”

Nielsen echoed President Donald Trump’s claims that a law is behind the recent spike in separations of migrant children and their parents at the border.

“We will not apologize for enforcing the laws passed by Congress,” Nielsen said. “We are a nation of laws. We are asking Congress to change the laws.”

However, as Harris and numerous fact checkers have noted, there is no law that mandates the separation of children and parents at the border.

Harris said in a statement Monday that Nielsen’s “misleading statements ... are disqualifying.”

“We must speak the truth,” Harris said. “There is no law that says the Administration has to rip children from their families. This Administration can and must reverse course now and it can and must find new leadership for the Department of Homeland Security.”

Update 2:30 p.m. June 18: Former Secretary of State Hillary Clinton said Monday that President Donald Trump is telling an "outright lie" when he claims that Democrats are behind the recent surge in separations of children from their parents on the border.

“This is not happening because of the 'Democrats' law,' as the White House has claimed,” Clinton said. “Separating families is not mandated by law at all.”

Clinton, who ran as a Democrat against Trump during the 2016 presidential election, also appeared to chastise U.S. Attorney General Jeff Sessions, who cited a Bible verse last week while justifying the Trump administration’s immigration policy.

“Those who selectively use the Bible to justify this cruelty are ignoring a central tenant of Christianity,” Clinton said. “Jesus said, ‘Suffer the little children unto me.’ He did not say, ‘Let the children suffer.’”

Update 2 p.m. EDT June 18: Former Florida Gov. Jeb Bush urged President Donald Trump to end the policy that's allowed authorities to separate migrant children from their parents on the border, writing Monday on Twitter that "children shouldn't be used as a negotiating tool."

“(Trump) should end this heartless policy and Congress should get an immigration deal done that provides for asylum reform, border security and a path to citizenship for Dreamers,” he wrote.

The president has repeatedly called for Democrats to negotiate with Republicans to address illegal immigration after falsely claiming that the party is behind laws that mandate the separation of child from parent at the border. No such law exists.

Jeb Bush, brother of former President George W. Bush and son of former President George H.W. Bush, ran against Trump in 2016 for the Republican presidential nomination.

In an op-ed published Sunday by the Washington Post, former first lady Laura Bush called the Trump administration policy "cruel."

"I live in a border state," Bush wrote. "I appreciate the need to enforce and protect our international boundaries, but this zero-tolerance policy is cruel. It is immoral. And it breaks my heart."

First lady Melania Trump has also criticized the policy, telling CNN in a statement through her spokeswoman that "She believes we need to be a country that follows all laws, but also a country that governs with heart."

Update 12:46 p.m. EDT June 18: President Donald Trump again accused Democrats of obstructing efforts to deal with illegal immigration and the separation of children and parents at the border, telling reporters Monday that "we're stuck with these horrible laws" because Democrats refuse to sit down with Republicans.

There are no laws mandating the separation of children and parents at the border.

“We have the worst immigration laws in the entire world,” Trump said. “Nobody has such sad, such bad – and in many cases, such horrible and tough – you see about child separation. You see what’s going on there.”

“The United States will not be a migrant camp and it will not be a refugee holding facility,” Trump said.

Update 12 p.m. EDT June 18: U.S. Attorney General Jeff Sessions on Monday said authorities don't want to separate children from their families but that officials have a duty to prosecute people who illegally cross the border.

“When we ignore our laws at the border we obviously encourage hundreds of thousands of people a year to likewise ignore our laws and illegally enter our country, creating an enormous burden on our law enforcement, our schools, our hospitals and (our) social programs,” Sessions said Monday during the National Sheriffs’ Association Annual Conference in New Orleans.

He framed the issue as a debate over “whether we want to be a country of laws or whether we want to be a country without borders.”

“President Trump has said this cannot continue,” Sessions said. “We do not want to separate parents from their children. If we build the wall, if we pass legislation to end the lawlessness, we won’t face these terrible choices. We will have a system where those who need to apply for asylum can do so and those who want to come to this country will apply legally.”

Sessions’ arguments echoed those of President Donald Trump, who has blamed Democrats for passing laws that he said led to the separations.

There are no laws mandating the separation of children and parents at the border.

Homeland Security Secretary Kirstjen Nielsen said earlier Monday that officials will not apologize for enforcing immigration laws.

"We have to do our job," she said.

Original report: President Donald Trump defended his administration's "zero tolerance" immigration policy on Monday, writing in a series of tweets that children are being used "by the worst criminals on earth" to get into America as critics slammed the policy for separating children from their parents.

“Children are being used by some of the worst criminals on earth as a means to enter our country,” Trump wrote. “Has anyone been looking at the Crime taking place south of the border. It is historic, with some countries the most dangerous places in the world. Not going to happen in the U.S.”

The president pointed to a rise in crime in Germany as an example of the chaos caused by illegal immigration, writing in a tweet that it was a “big mistake made all over Europe in allowing millions of people in who have so strongly and violently changed their culture.”

However, Germany's internal ministry reported last month that criminal offenses in the country were at their lowest since 1992, according to Reuters.

This spring, the Trump administration ordered prosecutors to charge every person illegally crossing the border. Children traveling with the adults have been separated and placed in detention centers, prompting protests nationwide.

The president has blamed Democrats for not fixing the law that allows for the separations.

“Tell them to start thinking about the people devastated by Crime coming from illegal immigration,” the president wrote. “Change the laws!”

Despite his claim that Democrats are at fault for the situation, The Associated Press reported that the Trump administration "put the policy in place and could easily end it."

The Associated Press contributed to this report.