Sen. Patrick J. Leahy, in his role as the president pro tempore, will preside over the Senate’s second impeachment trial of former President Donald Trump, an event that got closer to reality with the House transmitting an article of impeachment to the Senate on Monday.

“I’m not presenting the evidence. I am making sure that procedures are followed. I don’t think there’s any senator who over the 40-plus years I’ve been here [who] would say that I’ve been anything but impartial in ruling on procedure,” the Vermont Democrat said on Monday.

Promptly at 7 p.m., House Clerk Cheryl L. Johnson led the procession of the impeachment article, tucked a in large dark folder under her right arm, across the Capitol Rotunda.

She was joined in the procession by acting House Sergeant-at-Arms Timothy P. Blodgett and the nine House Democrats serving as impeachment managers. The group was silent and expressionless as they walked to the Senate chamber to exhibit the article.

There had been some legal uncertainty about who would preside over Trump’s second trial since a former president has never been impeached before, so this decision will set a precedent. The president pro tempore presides over impeachment trials when the individual impeached is not the current president. 

[Will Chief Justice Roberts preside at Trump’s impeachment trial? Maybe]

Supreme Court Chief Justice John G. Roberts Jr. presided over Trump’s first impeachment trial last year. That was in keeping with the Constitution, which states, “When the President of the United States is tried the Chief Justice shall preside.”

But the Constitution does not specify who would preside over the trial of a former president, nor does it even envision such a circumstance. Some Republicans have argued that holding an impeachment trial with Trump out of office would be unconstitutional, but Democrats and others, including many legal experts, say it is allowed and there is a precedent for trying officials after they have left office.

The question about the constitutionally of the trial is likely to be debated when the House impeachment managers and Trump’s defense team file legal arguments in the coming weeks and in their oral arguments when the trial begins the week of Feb. 8.

“I think it’s a sham impeachment. If the chief justice isn’t coming over, it’s just a partisan farce. … The Constitution says you can only impeach the president, and it says if you impeach the president, the chief justice shall preside,” Kentucky Republican Sen. Rand Paul said Monday.

In a sign that Republicans might be on the same page heading into the trial, Sen. Richard M. Burr of North Carolina also cast doubt on the way the proceedings were unfolding.

“If you read the instructions for the trial, if it’s a president, the chief justice of the Supreme Court is supposed to do it. If it is a judge, it can fall to somebody else. This is neither. This is a civilian now. A charge like this would go to the Justice Department and be referred for prosecution. Unfortunately, that’s not what they’re doing,” Burr said.

Leahy presiding over the trial puts him in a position where the Vermont Democrat will likely try to appear neutral throughout the proceedings but will be attacked for any decisions he makes that could be perceived as partisan. Ultimately, as one of the 100 senators charged with determining Trump’s fate, Leahy will get to cast a vote on whether to convict or acquit Trump at the end of the trial.

On Tuesday, senators will be sworn in and Trump will be sent a summons to register his plea, which is due Feb. 2. And the presentation of arguments in the trial won’t begin before Feb. 9.

The return procession, in which Johnson led the managers back to the House side sans impeachment article, was equally solemn.

“It felt historic, only the fourth time in history,” Rep. Ted Lieu, one of the managers, told CQ Roll Call. The California Democrat declined to answer other questions about the managers’ plans for prosecuting the case against Trump, saying, “I’m a former prosecutor and we don’t disclose trial strategy.”