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Senators were sworn in for the second impeachment trial of former President Donald Trump on Tuesday amid an immediate challenge to the constitutionality of the trial from a Republican ally of the former President.

Sen. Rand Paul of Kentucky forced a procedural vote on the constitutionality of the trial Tuesday afternoon, in what amounted to the first test of how Senate Republicans view the upcoming trial, the substance of which will begin with arguments next month. The Senate voted to table, or kill, Paul’s point of order, 55 to 45, with just five Republicans joining Democrats to vote against dismissing the trial.

The five Republicans who voted against Paul were Sens. Mitt Romney of Utah, Ben Sasse of Nebraska, Susan Collins of Maine, Lisa Murkowski of Alaska and Pat Toomey of Pennsylvania.

The Kentucky Republican said Tuesday that he forced the procedural vote to show there already aren’t sufficient votes to convict Trump, which would require two-thirds of senators. Many Republicans have taken the position in recent days that the trial is not constitutional because Trump is no longer President, in what’s become the most common argument to acquit Trump.

“I think it showed that impeachment is dead on arrival,” Paul said after the vote. “If you voted it was unconstitutional, how in the world would you ever vote to convict somebody for this?”

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Tuesday’s test vote showed that it’s likely next-to-impossible for Democrats to find 17 Republican votes for the two-thirds needed to convict and bar Trump from running for office again. Several Republicans said they were surprised Tuesday they were already taking a vote on the constitutionality of the trial, as the question is something that both the House impeachment managers and Trump’s legal team are likely to address in their presentations next month.

Senate Minority Leader Mitch McConnell, who has said he’s going into the trial with an open mind about Trump’s guilt, voted with Paul on Tuesday, suggesting he has constitutional concerns about the trial.

The trial began Tuesday afternoon with the swearing in of Sen. Pat Leahy of Vermont, the Senate president pro tempore, who will preside over the trial. Leahy then swore in the rest of the Senate, and senators went four at a time to sign an “oath book” as jurors for the trial.

David Carle, a spokesman for Leahy, said Tuesday evening that the senator was not feeling well after performing his duties and was taken to a local hospital.

“This evening, Senator Leahy was in his Capitol office and was not feeling well. He was examined in the Capitol by the Attending Physician,” Carle said in a statement. “Out of an abundance of caution, the Attending Physician recommended that he be taken to a local hospital for observation, where he is now, and where he is being evaluated.”

The Senate passed its pre-trial organizing resolution, laying out the rules heading into the trial, 83-17, before the Senate adjourned as a “court of impeachment” until February 9, when the trial arguments are scheduled to begin.

Republicans focus on constitutionality question

At their party lunch Tuesday ahead of Paul’s planned vote, Senate Republicans hosted conservative legal scholar Jonathan Turley, one of the lead scholars arguing that impeaching Trump when he is out of office is unconstitutional.

Turley has written extensively in recent days about his belief that while reasonable people can disagree about whether or not it is constitutional to hold an impeachment trial for a former President, he wrote recently on his blog, “even if the Senate does not view this as extraconstitutional, it should view this trial as Constitutionally unsound.”

Given the limited language in the Constitution on impeachment, legal experts disagree about whether the Senate can convict a former president. But Democrats have pointed to legal scholars on both ends of the political spectrum who say a trial is constitutional, because the Senate has held trials previously for former officials.

Sen. Dick Durbin, an Illinois Democrat, charged that Republicans were fixated on the constitutional issue because “they don’t want to be held accountable for President Trump’s incitement of a mob to attack the United States Capitol.”

“They don’t want to be held accountable on that vote so they’re going to try to make it another argument that is all about the Constitution,” Durbin said.

Several Senate Republicans say they agree it’s constitutional, including Sen. Mitt Romney of Utah and Lisa Murkowski of Alaska, who said her review “has led me to conclude that it is constitutional, in recognizing that impeachment is not solely about removing a president, it is also a matter of political consequence.”

Sen. Thom Tillis, a North Carolina Republican who just won reelection, said Tuesday, “I think there’s probably a constitutional basis for it.”

“I have more problem with the process and the expedited nature of it,” he added.

Several Republicans have pointed to the fact that Chief Justice John Roberts will not be presiding over the trial, while the Constitution says the chief justice should preside for the trial of a president.

“That would send a pretty clear signal to me what Roberts thinks of the whole thing,” said Sen. Chuck Grassley, an Iowa Republican, who declined to say how he would vote on Paul’s motion.

House managers prepare their case

On Monday, the House impeachment managers, a group of Democratic lawmakers who will act as prosecutors presenting the case against Trump during the trial, delivered the single article of impeachment to the Senate. The article, approved by the Democrat-led House, charges Trump with incitement of insurrection for provoking the attack on the US Capitol that left multiple people dead.

The two-week break until the trial begins will give both sides more time to prepare for the trial. Trump is still hiring lawyers for his impeachment legal defense team, which is being led by South Carolina lawyer Butch Bowers.

As the House impeachment managers put together their plans for the trial, they are considering using a variety of video evidence to show how the rioters were responding to Trump’s own words when they breached the Capitol, according to sources familiar with the deliberations.

The impeachment managers are still wading through the huge amount of video that exists from January 6 to determine what they should use at the trial, the sources said, including video posted to the conservative social media site Parler. The House’s impeachment team has taken an interest in a 10-minute video compilation from the national security forum Just Security, which uses social media posts from rioters on Facebook and Parler to illustrate how they were reacting in real-time to Trump’s comments at the January 6 rally as well as Trump’s social media posts when they attacked the Capitol.

No decisions have been finalized about how to use the video. The Washington Post first reported on the impeachment managers’ interest in the Just Security clip.

At the first Trump impeachment trial, House impeachment managers also used video to bolster their case that Trump had pushed for Ukraine’s help to investigate his political opponent, Joe Biden. The use of video for the upcoming trial is even more compelling given the disturbing images and video that have emerged of rioters ransacking the Capitol and attacking police officers.

The transmission of the article typically triggers a quick start to an impeachment trial, but Senate Majority Leader Chuck Schumer and McConnell reached a deal last week to push back the start date for the substance of the proceedings. That move will give Democrats more time to confirm Biden’s Cabinet and potentially take up a new Covid-19 relief bill while Trump’s defense team will have more time to prepare for trial.

It remains to be seen how long the trial will last, whether the House impeachment managers will seek witnesses and what the exact contours of the President’s legal defense will be.

When the trial gets underway, one visible difference between the proceedings and Trump’s first impeachment trial will be that instead of Roberts, the president pro tempore of the Senate, Leahy, will preside.

It would take a two-thirds vote in the Senate to convict Trump, a high bar to clear that looks increasingly unlikely to happen as a number of Senate Republicans are already arguing that it’s illogical and may be unconstitutional to impeach a former president.

Under the agreement reached by Schumer and McConnell, several ceremonial functions of the trial will take place this week. On Tuesday, the Senate is also expected to issue a summons to Trump, another step in the process of organizing for the trial to kick into high gear.

Then the trial will effectively be put on hold as the impeachment managers and Trump’s legal team exchange pre-trial briefs for two weeks. The final briefs would be due on February 9, allowing the trial to begin in earnest.

This story has been updated with additional developments Tuesday.