President Trump's defense team is set to conclude its arguments on Tuesday as Democrats continue to push Republicans to allow new witnesses, particularly former national security adviser John Bolton.
On Monday, most of the president's attorneys sidestepped a report about potentially explosive accusations in Bolton's upcoming book. The New York Times reported on Sunday that Bolton's manuscript personally implicates Mr. Trump in a scheme to delay $391 million in military aid to Ukraine until the country pursued investigations into his political rivals.
Alan Dershowitz, a member of the president's legal team, eventually confronted the allegations in a primetime presentation from the Senate floor Monday night. He argued that "nothing in the Bolton revelations, even if true, would rise to the level of an abuse of power or an impeachable offense."
A handful of Republican senators, namely Mitt Romney and Susan Collins, expressed an openness to calling Bolton to testify. Four Republicans would be needed to pass a motion allowing witnesses in an upcoming phase of the trial.
Tuesday is the last day for the president's team to deliver presentations, with proceedings getting underway at 1 p.m. Senators will then have 16 hours to submit written questions to the president's team and the House managers prosecuting the case.
Republican Senator Pat Toomey of Pennsylvania has raised with colleagues the idea of an agreement with Democrats in which each side would be allowed to call a single witness. The Washington Post first reported the "one-for-one" proposal on Monday.
There was some discussion of the idea among Senate Republicans at a lunch on Monday, but nothing solid or definitive emerged, a GOP Senate adviser told CBS News. Romney also spoke strongly about the need for Bolton to testify, this person said.
It's unclear whether there is any support for such a deal among Democratic senators, who have been universally opposed to calling Hunter Biden to testify.