Sen. Susan Collins, R-Maine, and Sen. Richard Burr, R-N.C., arrive as senators go to the chamber for votes Thursday at the Capitol. J. Scott Applewhite/Associated Press

A frustrated Sen. Susan Collins said Friday that she believed a commission to investigate how and why violent protesters loyal to former President Donald Trump were able to breach security and lay siege to the Capitol on Jan. 6 was necessary to prevent a similar calamity in the future.

Despite a weekslong effort to persuade at least 10 of her fellow Republicans to join her, Collins was on the losing side of a vote Friday to bring a bill, passed by the U.S. House, to the floor of the Senate for debate. Maine’s other senator, independent Angus King, also voted Friday to move forward with the commission.

The vote to move the bill forward needed 60 votes in the 100-seat Senate but fell six votes short, with 54 senators in favor and 35 opposed. Another 11 senators (nine Republicans and two Democrats) skipped the vote entirely.

In an interview with the Press Herald just ahead of the vote, Collins lamented that the country now may never get an unvarnished and objective account of how an angry mob managed to storm into the Capitol, leaving five people dead and more than 140 law enforcement officers injured. Earlier in the week, Collins was among a small number of Republicans to meet with the longtime girlfriend of Capitol Police Officer Brian Sicknick, who died as a result of strokes he suffered during the riot.

She said Congress owed it to those officers who “saved our lives” to get to the bottom of what happened Jan. 6.

Her stance again puts Collins at odds with her party and Senate Minority Leader Mitch McConnell, R-Kentucky, who opposed the bill despite amendments proposed by Collins meant to alleviate McConnell’s objections to the composition of the commission and the timeline for its work. McConnell also worked to lobby members to vote against it, even as Collins was trying to build support.

Collins was among six Republicans to move forward with a vote on the commission. Five of those six, including Collins, also voted to convict Trump during a failed impeachment trial this year for his role in egging on the rioters during a rally beforehand and on social media as it ensued.

“We are living in a highly polarized, hyper-partisan environment where each side is suspicious of the other side’s motives,” Collins said. She noted that many of her Senate colleagues were not there when Congress approved a commission to investigate 9/11, which resulted in federal reforms that bolstered national security against terror attacks launched by entities from outside of the United States.

Collins said Democrats would now likely move forward with their own select committee to investigate the attack and that the results of that investigation would lack credibility with Republicans, although it would still likely garner widespread national attention, “because it will be the only investigation going on and the press will treat it as if it is an independent outside commission, which it will not be.”

“That is likely to be the terrible outcome, if we do not create a truly outside, independent commission that can take an unbiased, hard look at what happened,” she said.

King, an independent who caucuses with Democrats, criticized Republicans who voted against the commission.

“This was one of the darkest moments in American history, the worst attack on our democracy since the Civil War, and we need to understand what went wrong so we can prevent similar crises in the future,” King said in a statement. “However, today the majority of my Republican colleagues in the Senate made it clear that they have little interest in looking at the facts; instead, they’d rather ignore or minimize the whole event. When people are moving heaven and earth to block an investigation, you’ve got to ask what it is they’re afraid will be revealed.”

Over the past week, Republican senators voiced concern that even if the commissioners’ ranks were bipartisan, the panel’s staffing might not be. They also argued that if the commission failed to produce a final report before the end of the year, Republican lawmakers would have to spend much of the 2022 campaign season responding to its revelations about Trump’s past ills and trying to sidestep his outbursts when their aim is to make the next election cycle a referendum on President Biden and the Democrats who control Congress.

Collins tried to address both points with an amendment that would have required the commission’s chair and vice chair to make hires together, and shortened the time it would have to wind down its work after a Dec. 31 deadline to issue a final report. But while her proposed changes generated a flurry of last-minute activity around the bill, they never came to a vote on the floor.

According to the Washington Post, Collins had a visibly angry reaction, confronting Senate Majority Leader Chuck Schumer of New York, and accusing him of undermining the vote by failing to declare ahead of time that he and the Democrats would back her changes, if the measure to take up the bill advanced.