The U.S. Senate returned to business Friday after its holiday break, and the leaders of both parties took to the floor to again decry how the other side is behaving over President Donald Trump’s stalled impeachment trial.

“No one needs any lectures from House Democrats on fairness,” said Senate Majority Leader Mitch McConnell. “House Democrats have blown right past the specific warnings of the founding fathers. And they continue their political delay and search desperately for new talking points to deflect the blame for what they’ve done.

“So, for now, we’re content to resume the ordinary business for the senate while House Democrats continue to flounder.”

Senate Minority Leader Chuck Schumer doubled down on his insistence that witnesses be called to testify in the trial.

The Impeachment Process: Explained.Impeachment is the political process of removinga civil officer from office for reasons of “treason,bribery, or other high crimes and misdemeanors.”.It can be brought against eventhe highest officials, such as thePresident and Vice President. .The process begins in the U.S. House of Representatives, where a suggestion to impeach must be made and then authorized to proceed by the Speaker of the House.From there, the speaker chooses to move the inquiry to either a

The Senate is still waiting on House Speaker Nancy Pelosi to send over Trump's articles of impeachment, the next step in an impeachment trial.

Despite Democrats' professed sense of urgency in passing House impeachment articles against the president last month, Pelosi has delayed sending the charges over to the Senate and refused to name the House managers who would handle the trial until Senate GOP leaders meet her demands.

Pelosi is demanding information from the Senate on how it plans to conduct Trump’s trial and hopes to give Senate Minority Leader Chuck Schumer of New York more leverage in talks with McConnell.

McConnell reiterated Friday morning his decision that Trump’s impeachment trial − should it ever happen − would proceed along the same lines as Bill Clinton’s in 1999. Schumer, however, wants to call witnesses that would presumably drag Trump’s trial out into a White House election year.

»MORE: More senators breaking ranks from their parties on Trump impeachment

Some key senators are beginning to show dissension within their party ranks.

On Monday, Sen. Susan Collins, R-Maine, slammed fellow Sens. Elizabeth Warren and McConnell for making comments ahead of the impeachment trial before it's even been officially scheduled.

»MORE: Anti-Trump GOP groups upping pressure on Senate Republicans

Collins joined Sen. Lisa Murkowski, R-Alaska, in criticizing McConnell's comments in December that the Senate will work in "total coordination" with the White House in developing Trump's defense.

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.

Also, Sen. Doug Jones, D-Alabama, has indicated he is open to supporting Trump if the House has not made a strong enough case against the president.

»MORE: Alabama Democrat may support Trump in impeachment trial

On Friday, McConnell said impeachment is not a narrow judicial decision but “a deeply political one.”

Trump is only the third sitting president in American history to be impeached, joining Andrew Johnson and Clinton.

The two articles of impeachment by House Democrats — abuse of power and obstruction of Congress — point to Trump pressuring Ukraine to investigate 2020 political rival Joe Biden while withholding as leverage military aid the country relies to counter Russia as well as his efforts to block the House investigation.

»MORE: Which U.S. presidents have faced impeachment?

The Constitution requires a two-thirds majority in the Senate to convict in an impeachment trial, thus making Trump’s actual removal from office highly unlikely in the GOP-controlled Senate.