As procedural votes were underway in the House, Speaker Nancy Pelosi went outside the Capitol to thank the National Guard troops deployed to the complex in the wake of last week's riot and ahead of Biden's inauguration in one week.

Some National Guard members inside the Capitol were spotted taking in the sights of the Rotunda Wednesday morning, gathering around and listening to Rep. Brian Mast, R-Fla., an Army veteran who lost both legs in Afghanistan.

The Capitol has been closed to tours for months due to the coronavirus pandemic. With the exception of last Wednesday's attack, this is one of the few times visitors have snapped photos inside the building during the pandemic -- finding themselves with unique access as they've been designated to protect the building and lawmakers.

As lawmakers arrived on the Hill ahead of the House gaveling in to consider Trump's second impeachment, a heavy National Guard presence greeted them both outside and inside the building -- with some resting, embracing their rifles, on the floor of the Capitol.

Jane Campbell, the president and CEO of the United States Capitol Historical Society, confirmed to ABC News that troops have not been quartered in the Capitol since the Civil War -- when the Rotunda was still under construction, and the open-air space was used as a field hospital.

A Defense official said the National Guard members seen sleeping at the Capitol are on breaks and noted that it’s not uncommon on domestic or overseas deployments to see members taking breaks in between long shifts.

There are currently 6,600 members of the National Guard in Washington, D.C. with more continuing to flow in. A Defense official said Wednesday afternoon that the National Guard has now been authorized to have up to 20,000 Guardsmen in Washington for inauguration security and that most may be in town by this weekend.

-ABC News Luis Martinez and Benjamin Siegel

The first vote broke down along party lines 221-205, with Democrats voting to advance proceedings. Seven House members did not vote.

The House is now voting on the rule, which is expected to take roughly 45 minutes to one hour, the same amount of time. The chamber will then move to begin debate on the impeachment article.

-ABC News' Benjamin Siegel

As part of rule debate leading up to debate on the article of impeachment, Republicans have largely focused on procedural concerns, criticizing Democrats for moving quickly to impeach Trump without a full investigation and suggesting the move would further divide Americans.

"I hold him accountable for the attack on the Capitol," newly elected Rep. Nancy Mace, R-S.C., said, making her first speech on the House floor.

"If we're serious about healing the divisions in this country, Republicans and Democrats need to recognize that last week wasn't the first day of violence," she continued. "There is violence on both sides of the aisle."

"President Trump will leave office in seven days," Rep. Jason Smith, R-MO, said. "This is a reckless impeachment ... have a conscience."

Rep. Jim Jordan, R-Ohio, attacked Democrat Rep. Jim McGovern, the chairman of the House Rules Committee, over his 2017 objection to the election results, and accused Democrats of hypocrisy.

McGovern quickly shot back that Democrats and Hillary Clinton recognized Trump's victory -- when Republicans refused to acknowledge Biden's.

"The bottom line is this. This Capitol was stormed -- people died because of the big lies that were being told by this president and by too many other people on this side of the aisle. Enough!" McGovern said. "Coming up on this floor and talking about whataboutism and trying to make these false equivalences -- give me a break."

"The president of the United States instigated an attempted coup in this country," he added. "If this is not an impeachable offense I don't know what the hell is."

-ABC News' Benjamin Siegel

Several conservative House Republicans have criticized Rep. Liz Cheney since she announced she would support impeachment Tuesday evening.

The Wyoming Republican is the chair of the House GOP conference -- the No. 3 leadership position -- and was reelected to by GOP members at the start of this Congress.

"We ought to have a second vote," Rep. Jim Jordan, R-Ohio, told reporters Wednesday about the leadership position. "The conference ought to vote on that."

"She should not be serving this conference," Rep. Andy Biggs, R-Ariz., said Tuesday.

It's unclear how widespread the effort to remove Cheney from GOP leadership is. But Trump's top allies in the House are using impeachment as an opportunity to kneecap Cheney, a potential future speaker, after months of simmering tensions.

-ABC News' Benjamin Siegel

Rep. Steve Scalise, R-La. -- the No. 2 Republican in the House -- was the last to speak for the Republican Party, said he opposed the "rushed" impeachment, and emphasized that the Senate will only be able to take up the trial once Trump is out of office.

"I've seen the dark evil of political violence firsthand. And it needs to stop. But all of us need to be unequivocal in calling it out every single time we see it, not just when it comes from the other side of the aisle," he said.

Invoking President Abraham Lincoln, he closed by calling on Americans to unify and "seek higher ground."

House Judiciary Chairman Rep. Jerry Nadler, D-N.Y., quickly responded to his remarks, saying, "We can have all this, and we can have accountability too," before handing off to Majority Leader Rep. Steny Hoyer, D-Md.

Hoyer, in a scathing rebuke of the president, repeated the words of Rep. Liz Cheney and called on his Republicans colleagues to rise to the moment and join her to "reject the vices we abhore."

"It is the first and only physical presence other than the 9/11 attack on this nation -- which came from abroad with a plane aimed at our Capitol dome. This attack was not from abroad. It was as Liz Cheney said, summoned, assembled, and inflamed by the president of the United States of America," he said.

"Last Wednesday, on Jan. 6, the nation and the world watched it shatter to pieces. There could be no mistaking any longer the kind of man sitting in the Oval Office or his intentions and capabilities. The curtain has been pulled back. The office to which he was elected could not temper or reform him," Hoyer said.

"Reject deceit. Reject fear mongering. Reject sedition, tyranny and insurrection," Hoyer said. "Reject one man over fidelity to one's country."

Hoyer noted that soon the House Reading Clerk will call the roll for voting, and added, "Make no mistake, this will be no ordinary roll call."

"These votes will be inscribed on the roll of history -- a record of courage -- and of our commitment to country and Constitution, of our commitment to the rule of law and renewal of that which we inherited and hope to pass on, unbroken, unshattered," he said. "Vote for this -- for America, for our constitution, for democracy, for history."