After hearing opening arguments and questioning from House impeachment managers and the White House counsel, the Senate is expected to take a vote on whether to consider the witness issue at all, according to senators familiar with McConnell’s plans. If the Senate agrees to hear witnesses, every senator will have the chance to force a motion seeking testimony.

An initial vote to consider witnesses has been sought by GOP Sens. Susan Collins of Maine, Mitt Romney of Utah and Lisa Murkowski of Alaska. If it fails, the trial is likely to head to closing arguments. The question of witnesses might mimic the motion to dismiss impeachment that was considered and rebuffed during former President Bill Clinton’s Senate trial.

Both Collins and Murkowski said on Wednesday they aren’t advocating for specific witnesses but simply want to retain the right to hear more evidence during the trial. Collins even said she agrees with Paul’s view on witness parity.

“If he’s saying that both sides should have an opportunity, I agree with that, to call witnesses. We’ll make the call on which ones. But it isn’t fair to just let one side call witnesses,” she said.

But asked about Paul’s contention that she and other Republicans risk a collapse in support from the GOP base if they side with Democrats on procedural votes, she demurred: “You know, it’s not my focus. My focus is to be fair. And to have a dignified trial.”

Paul is perhaps the most aggressive user of Senate procedure to get his way, forcing votes on budget-cutting amendments on spending bills; briefly shuttering the Patriot Act; and even forcing his a brief government shutdown in 2018. And he often draws significant blowback from his party for his tactics.

But this time around, Paul is acting as his own version of a team player. He’s not going to offer a motion to immediately dismiss the trial despite pressure from Trump’s allies to do so. He’s even talking about party unity — even though he’s usually the most likely Republican to deviate from McConnell’s line.

“Sometimes it’s good to have people unified. ... I’m for immediate dismissal, but I know it’s not just four [senators]. There might be 10 that are against immediate dismissal. It’ll just be a vote that fails,” Paul said. “When it’s something that we’re trying to stay together and there is the other team trying to attack our leader, I think it behooves us to have as much unanimity as we can.”