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

As senators questioned both the Trump legal team and the Democratic managers of the trial, Trump lawyer Alan Dershowitz offered an expansive defense of presidential power that provoked astonishment among Democrats.

“If a president does something which he believes will help him get elected in the public interest, that cannot be the kind of quid pro quo that results in an impeachment,” Dershowitz said, referring to the charge that Trump abused his power by using congressional approved security aid as leverage to get a foreign power to smear his political rival, Joe Biden.

Democratic Senator Mazie Hirono told reporters: “That was one of the most bizarre things I’ve ever heard as a response.”

Senator John Barrasso, the third-most senior Republican, said it was possible the trial could end on Friday without witnesses being called, as Democrats want.

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

Asked when 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 Wednesday’s proceedings.

The Democratic-led House of Representatives approved the two articles of impeachment being heard in the Republican-controlled Senate in December. Democrats have sought to persuade at least four Republican senators to vote with them in favor of witnesses to assure a majority vote in the 100-seat chamber.