Maine’s independent senator had submitted 13 questions as of Wednesday afternoon, 4 of which were selected by the Senate minority leader to be asked during the president’s trial.

Sens. Collins, Romney and Murkowski ask if senators should consider more than 1 motive to assess whether the president abused his power.

Alan Dershowitz tells senators that, in the matter of impeachment, it doesn’t matter if the president traded U.S. military aid for political favors.

Senators are warned that if they agree to call Bolton to testify or try to access his book manuscript, the White House will block him, beginning a weekslong court battle over executive privilege and national security.

The president’s defense lawyers make no direct reference to revelations about John Bolton’s book, but it’s clear that the development has scrambled the debate over whether to seek witnesses.

The debate over witnesses received a jolt Sunday when The New York Times reported that Trump told his national security adviser he wanted to maintain a freeze on military aid to Ukraine until it launched political investigations into his rivals.