Sen. Susan Collins (R-Maine) put the Democrats one vote closer to calling additional witnesses late Thursday night after the Senate adjourned, announcing she will vote with them on Friday.

Minutes later another closely watched Republican, Sen. Lamar Alexander (Tenn.), made it unlikely the vote will pass, but could tie if all members of the Democratic caucus and two more Republicans vote yes.

Senators reconvened for a second day of questions to House impeachment managers and President Trump’s lawyers ahead of a crucial vote expected Friday on whether to call witnesses to testify about the president’s conduct toward Ukraine.

Democrats are pressing to call witnesses, including former national security adviser John Bolton, but Senate Majority Leader Mitch McConnell (R-Ky.) and other leading Republicans do not want to extend the proceedings into unpredictable territory and are angling for a swift acquittal of Trump.

The president team has focused on process, the fact that Schiff did not subpoena Bolton during the House’s inquiry. Schiff has shot back that Bolton refused to testify and threatened to sue the House if subpoenaed. Now he’s willing to testify, so the Senate should call him, Schiff has argued.

Trump faces charges of abuse of power and obstruction of Congress. The crux of the case for his impeachment is the allegation that he withheld military aid and a White House meeting to pressure Ukraine to investigate Joe Biden and his son. Hunter Biden served on the board of Burisma, a Ukrainian energy company, while his father was vice president.

●Trump legal team advances blanket defense against impeachment.

●Wavering Democrats face pressure as GOP eyes bipartisan vote for Trump acquittal.

●Bolton’s lawyer contends his book does not contain classified material and asks White House for expedited review so he can testify if called.

●All the president’s disloyal men? Trump demands fealty but inspires very little.