A Democratic push to force Republicans to accept witnesses at Donald Trump’s impeachment trial in the U.S. Senate appeared to be flagging on Wednesday, raising the possibility the president could be acquitted as early as Friday.

As senators spent the day posing questions to both the Trump legal team and the Democratic managers of the trial, the White House objected to the planned publication of a book by former national security adviser John Bolton, who is said to have depicted Trump as playing a central role in pressuring Ukraine to investigate Democratic rival Joe Biden.

U.S. Senator John Barrasso, the No. 3 Republican in seniority, said it was possible the trial could end on Friday without Democrats achieving their goal of having witnesses called to testify.

“The momentum is clearly in the direction of moving to final judgment on Friday. That vote will be Friday. We still have a couple members who said they want to listen to the answers to questions, but that’s where the momentum is,” Barrasso said.

Asked when Friday the vote might take place to settle the debate over witnesses and move to either acquit or convict Trump, Barrasso said probably Friday afternoon or late that day.

Other Republican senators were predicting a similar outcome in conversations with reporters during breaks in the trial on Wednesday. They said some of their colleagues still wanted to hear answers to their questions through Thursday, however.

Read more: Reuters