Trump impeachment trial live updates: Biden says charge 'not in dispute' in 1st comments on acquittal

After the Senate moved in a 55-45 vote to consider a resolution to call specific witnesses, Senate leaders are now meeting to draft that resolution.

According to sources, it should contain specific information on how the trial will move forward.

The resolution will be amendable, which means Republicans could offer endless amendments. Each amendment would get two hours of debate before a vote. Many want to avoid that situation, according to sources.

Sen. Chris Murphy, D-Conn., told ABC News the House managers could still decide to call no witnesses. In the end, the Senate will need to vote again on the resolution, which requires a simple majority vote to pass.

Lawmakers have begun to go back to their office building, so it appears the trial is in a holding pattern for some time.

-ABC News' Trish Turner

The Senate has called a recess until 12:30 p.m. as Senate leaders draft a resolution to call for witnesses in Trump's trial, following a 55-45 vote.

According to sources, the resolution -- which the Senate will need to vote on -- should contain specific information on how the trial will move forward.

Senators on both sides of the aisle seemed surprised by House impeachment managers' move to call for witnesses Saturday, according to pool reporters inside the chamber.

Sen. Ron Johnson, R-Wis., turned to Sen. Mitt Romney, R-Utah., at one point and was visibly upset with him, even pointing at him once. The two went back and forth with Sen. Dan Sullivan, R-Alaska, in the middle of them.

Johnson said, "We should've just ended this, that's all I'm saying," and told Romney, "Blame you."

Romney was the only Republican to vote to convict Trump at his last impeachment trial.

When lead House impeachment manager Rep. Jamie Raskin, D-Md., raised bringing in Rep. Jamie Hererra Beutler, D-Wash., as a witness, Sen. Lindsey Graham, R-S.C., shook his head no and put his head down on his hand on his forehead.

Graham later joined four Republicans --Sens. Mitt Romney, Susan Collins, Lisa Murkowski and Ben Sasse -- in voting to hear witnesses after threatening to delay the trial with witnesses of his own.

Sources close to Trump are floored by the unexpected, 11th-hour motion to call witnesses in the impeachment trial of the former president.

"Stunned," "stupefied," and "digesting this” were responses provided by sources to ABC News. There is total panic in the air as the question looms of who may get called as a witness and who may step up to help Trump's defense team. 

The development to call witnesses revolves around the timeline of Trump's response to the attack on Jan. 6 and when he knew then-Vice President Mike Pence was in danger.

David Schoen, one of Trump's impeachment lawyers, threatened to quit Thursday night -- just hours before he was to mount a defense of Trump's actions.

It wasn't until Trump called Schoen directly that he agreed to remain on the team. It also led to the speaking roles and order of the attorneys during the Friday defense presentation being altered, according to the sources.

ABC News' Katherine Faulders and John Santucci