Updated 5:40 p.m. ET
After senators were sworn in Tuesday afternoon as jurors in the impeachment trial of former President Donald Trump, Sen. Rand Paul quickly pressed for a vote to force lawmakers on the record over the issue of the trial's constitutionality.
The Senate voted 55-45 to reject the Kentucky Republican's argument that the impeachment trial is unconstitutional because Trump is no longer in office.
Just five Republicans — Sens. Susan Collins of Maine, Lisa Murkowski of Alaska, Ben Sasse of Nebraska, Mitt Romney of Utah and Pat Toomey of Pennsylvania — joined Democrats in voting to table the motion. Senate Minority Leader Mitch McConnell, R-Ky., notably voted with most of the GOP conference in support of Paul's motion.
A two-thirds majority is required for a Senate conviction. Paul's point of order likely foreshadows the intentions of most Republican senators during the trial and demonstrates how unlikely it is Democrats will garner the 17 Republican votes needed to convict Trump.
"I think [Tuesday's vote will] be enough to show that more than a third of the Senate thinks that the whole proceeding is unconstitutional, which will show that ultimately they don't have the votes to do an impeachment," Paul told Capitol Hill reporters Tuesday morning.
Collins told reporters after the vote she thinks it's "extraordinarily unlikely" that Trump will be convicted, bluntly saying: "Do the math."
Before the vote, Paul spoke on the Senate floor and called the impeachment effort a "partisan exercise."
"If the accused is no longer president, where is the constitutional power to impeach him? Private citizens don't get impeached. Impeachment is for removal from office, and the accused here has already left office," he said.
His argument is one that has been repeated often in recent days by other Senate Republicans, who have largely criticized Trump's actions leading up to and during the Jan. 6 insurrection on the U.S. Capitol (the basis for his second impeachment) but have questioned the constitutionality of trying him once he left office.
"The theory that the Senate can't try former officials would amount to a constitutional Get Out of Jail Free card for any president who commits an impeachable offense," Senate Majority Leader Chuck Schumer, D-N.Y., said in remarks ahead of the vote.
Rep. Jamie Raskin, D-Md., who is serving as one of the House impeachment managers, has also dismissed arguments from Republicans claiming the trial is unconstitutional.
"If we had a rule that you can't be tried for anything that you did in your last three or four or five weeks in office, that would basically be sending an extremely dangerous signal to future presidents that they could try to incite or execute a coup or an armed insurrection against the government and say, 'La-di-da, it's too late to prosecute me,' " Raskin told NPR's Kelsey Snell.
"The Constitution applies on your first day of office, it applies on your last day in office and everything in between," the former constitutional law professor added.
Sen. John Thune, R-S.D., told reporters the Tuesday vote doesn't bind lawmakers into voting one way or another after the trial.
"It was a question on the constitutionality of it," the Senate minority whip said. "I don't think it binds anybody once the trial starts. But I think most of us thought that the threshold issue of whether or not you can remove, as the Constitution suggests, somebody who's no longer in office is, [as] most of our members I think had concluded that, from a constitutional standpoint, it's on really shaky ground."
Sen. Rob Portman, who recently announced he won't seek reelection, echoed that sentiment, saying he still has questions on the constitutionality issue.
"This is a serious constitutional question, and today I voted for allowing debate on this issue and against tabling this important discussion," Portman said. "As the trial moves forward, I will listen to the evidence presented by both sides and then make a judgment based on the Constitution and what I believe is in the best interests of the country."
Romney told reporters earlier Tuesday that he disagrees with Paul's claims on the trial's constitutionality.
"The preponderance of opinion with regards to the constitutionality of a trial of impeachment of a former president is saying that it is a constitutional process," he said.