President Donald Trump’s lawyers opened their impeachment trial defense in a rare Saturday session by accusing Democrats of striving to overturn the results of the 2016 election, saying the Democrats’ investigations into his dealings with Ukraine were not a fact-finding mission but a politically motivated effort to drive him from the White House.

“They’re here to perpetrate the most massive interference in an election in American history,” White House Counsel Pat Cipollone told senators. “And we can’t allow that to happen.”

The Trump legal team’s arguments in the rare Saturday session were aimed at rebutting allegations that the president abused his power when he asked Ukraine to investigate political rival Joe Biden and then obstructed Congress as it tried to investigate. The lawyers are mounting a wide-ranging, aggressive defense asserting an expansive view of presidential powers and portraying Trump as besieged by political opponents determined to ensure he won’t be reelected this November.

“They’re asking you to tear up all the ballots across this country on your own initiative, take that decision away from the American people,” Cipollone said.

“They’re asking you not only to overturn the results of the last election, but as I’ve said before, they’re asking you to remove President Trump from an election that’s occurring in approximately nine months,” Cipollone said. “They’re asking you to tear up all the ballots across this country on their own initiative.”

Watch the trial here.

Though Trump is the one on trial, the defense team made clear that it intends to paint the impeachment case as a mere continuation of the investigations that have shadowed the president since before he took office — including one into allegations of Russian election interference on his behalf. Trump attorney Jay Sekulow suggested Democrats were investigating the president over Ukraine simply because they couldn’t bring him down for Russia.

“That — for this,” said Sekulow, holding up a copy of special counsel Robert Mueller’s report, which he accused Democrats of attempting to “relitigate.” That report detailed ties between the 2016 Trump campaign and Russia but did not allege a criminal conspiracy to tip the election.

From the White House, Trump tweeted his response: “Any fair minded person watching the Senate trial today would be able to see how unfairly I have been treated and that this is indeed the totally partisan Impeachment Hoax that EVERYBODY, including the Democrats, truly knows it is.”

His team made only a two-hour presentation, reserving the heart of its case for Monday.

Trump’s defense team took center stage following three days of methodical and passionate arguments from Democrats, who wrapped up Friday by warning that Trump will persist in abusing his power and endangering American democracy unless Congress intervenes to remove him before the 2020 election. They also implored Republicans to allow new testimony to be heard before senators render a final verdict.

“Give America a fair trial,” said Schiff, the lead Democratic impeachment manager. “She’s worth it.”

House prosecutors wrapped up their third and final day of their case Friday against the president, who was impeached last month on charges of abuse of power and obstruction of Congress.

U.S. House Democrats have drafted two articles of impeachment against President Donald Trump. House leaders are charging the president with abuse of power and obstruction of Congress. They announced the articles of impeachment on Dec. 10, 2019. A full House impeachment vote could come before Christmas. If passed, the president would face a Senate trial in 2020, a presidential election year.

“We will be putting on a vigorous defense of both facts, rebutting what they said,” and the Constitution, said Trump attorney Jay Sekulow.

On Wednesday, Thursday and Friday, Schiff and his team of House impeachment managers tried to convince often bored and tired senators that Trump should become the nation's first president to be removed from office.

Here are the key figures in President Donald Trump's impeachment trial. House Speaker Nancy Pelosi. She led the impeachment effort. Chief Justice John Roberts. He will preside over the trial. The Senate's political leaders - Majority Leader Mitch McConnell and Minority Leader Chuck Schumer. The president's legal defense team - White House counsel Pat Cipollone, Trump personal lawyer Jay Sekulow, Kenneth W. Starr, Alan Dershowitz, along with Robert Ray and Jane Raskin. House Democratic impeachment managers

Although uncommon, congressional calendars do list Saturday legislative days. President Bill Clinton's 1999 impeachment trial, which ran from Jan. 7 to Feb. 12, included several Saturday sessions.

President Bill Clinton was impeached on perjury and obstruction of Congress charges on Dec. 19, 1998. He was acquitted by the Senate on Feb. 12, 1999. Fourteen senators from that trial still remain in office. Here's how they voted. Susan Collins, R-Maine. Not guilty on both counts Michael D. Crapo, R-Idaho. Guilty on both counts Richard Durbin, D-Illinois. Not guilty on both counts Mike Enzi, R-Wyoming. Guilty on both counts Dianne Feinstein, D-California. Not guilty on both counts Charles Grassley, R-Iow

Trump himself appeared to be dismayed his defense team would begin making their case on a weekend.

The president is accused of abusing his office by asking Ukraine to investigate former Vice President Joe Biden and his son, Hunter, while allegedly withholding aid from a U.S. ally at war with bordering Russia. The second article of impeachment accuses him of obstructing Congress by refusing to turn over documents or allow officials to testify in the House probe.

»Read the best lines from President Trump’s Senate impeachment trial

Prosecutors on Thursday argued Trump abused power for his own personal political benefit ahead of the 2020 election, even as the nation’s top FBI and national security officials were publicly warning off the theory that it was Ukraine, not Russia, that interfered in the 2016 election.

On Friday, Democrats focused on the second article of impeachment, obstruction of Congress’ investigation.

7 Things to Know About How a Senate Impeachment Trial Works. 1. Senators take an oath to "do impartial justice.". Though Senate majority leader Mitch McConnell has stated, "I'm not an impartial juror," the wording of the required Constitutional oath is clear on the necessary impartiality. 2. A majority is needed in order to call a witness. President Donald Trump has indicated he'd like the whistleblower to be called as a witness, but more moderate Republicans could prevent such an occurrence. 3.

After the president’s defense team makes its arguments, senators will then have 16 hours to ask written questions and another four hours for deliberations. They will also then decide whether they want to call witnesses to testify.

The Senate is heading next week toward a pivotal vote on Democratic demands for testimony from top Trump aides, including acting chief of staff Mick Mulvaney and former national security adviser John Bolton, who refused to appear before the House.

It would take four Republican senators to join the Democratic minority to seek witnesses, and party lines appear to be strongly holding.

Impeachment was established in the U.S. Constitution as a way to accuse a president of a crime and then hold a trial to determine if guilty. The first step requires a U.S. House member to introduce an impeachment resolution. The House speaker directs the judiciary committee to hold a hearing to decide whether to put the full measure to a vote by the full chamber. A majority of the committee must approve the resolution. If approved, it moves to a full vote on the House floor. If a majority of the House vot

The U.S. Constitution requires a two-thirds majority in the Senate, or 67 senators, to convict in an impeachment trial.

Republicans hold 53 seats in the Senate, while Democrats hold 45. However, two Independents — including presidential candidate Bernie Sanders of Vermont — regularly caucus with Democrats, giving the nation’s blue party 47 votes.

If the Senate votes along party lines regarding impeachment — as did the House — 20 Republican senators would have to join Democrats in convicting Trump and removing him from office.

Donald Trump has become the third American president to be impeached. Trump has been charged with abuse of power and obstruction of Congress. Led by Democrats, the U.S. House of Representatives passed the articles of impeachment on Dec. 18, 2019. Trump will face trial in the GOP-controlled Senate in 2020, a presidential election year. Presidents Andrew Johnson and Bill Clinton were also impeached. Neither was removed from office.

The first article of impeachment passed by the House charges President Trump with abuse of power.

Democrats allege Trump “solicited the interference of a foreign government, Ukraine, in the 2020 U.S. presidential election. He did so through a scheme or course of conduct that included soliciting the government of Ukraine to publicly announce investigations that would benefit his reelection, harm the election prospects of a political opponent, and influence the 2020 U.S. president election to his advantage.”

The “election prospects of a political opponent” refer to Biden, currently a front-runner in a narrowing field of Democratic White House hopefuls.

The president “also sought to pressure the government of Ukraine to take these steps by conditioning official U.S. government acts of significant value to Ukraine on its public announcement of investigations.”

Democrats argue the president “used the powers of his presidency in a manner that compromised the national security of the United States and undermined the integrity of the United States democratic process. He thus ignored and injured the interests of the nation.”

The Associated Press contributed to this report.