Sen. Lamar Alexander, R-Tenn., who is set to retire at the end of his term, could provide the pivotal vote for witnesses in President Donald Trump's impeachment trial, NBC News reports.
Alexander's former chief of staff Tom Ingram told NBC, the senator is unpredictable, and his former campaign manager Mark Braden added, Alexander will "do what he believes is right regardless" of what people say.
"You can't predict" Alexander, Ingram said. "He will hold his counsel, make his own decision, and you won't be sure of it until he makes it known in due course."
Alexander, along with Sens. Mitt Romney, R-Utah, Susan Collins, R-Maine, and Lisa Murkowski, R-Alaska, have been targeted as Republicans who could side with Democrats on witnesses.
"After we've heard all the arguments, after we heard the questions and the answers to the questions and we've studied the record then we'll have that vote" on witnesses, Alexander said Monday. "And at that time, I'll make a decision about whether I think they need additional evidence."
The senator has repeatedly called for a vote on witnesses despite opposition from Senate Majority Leader Mitch McConnell, R-Ky.
"Worrying about what he's going to do may be natural for some, but it will not make any difference to [Alexander]," Ingram said. "He will make his own decision regardless of who is the president, his party, what his colleagues in the Senate may say, regardless of whether he is or is not seeking re-election, or how his legacy may be viewed, and he will have a clear conscience doing it."