Senate Republicans blocked bipartisan legislation on Friday that would have established an independent 9/11-style commission to investigate the Jan. 6 attack on the U.S. Capitol by Donald Trump supporters, testing Democratic holdouts over their support for the filibuster.

It also marked the second time since the violent insurrection in the nations capital that congressional Republicans shielded the former president from accountability for the events that transpired earlier this year.

If we cant agree to an independent commission investigating the first armed insurrection at the Capitol in our nations history then something is bad wrong. And that something is the filibuster, Sen. Elizabeth Warren (D-Mass.) said.

The vote tally was 54 to 35, but the bill needed 60 votes to move forward to further debate due to filibuster rules. Only six Republican senators joined Democrats in support of advancing the measure: Lisa Murkowski of Alaska, Mitt Romney of Utah, Susan Collins of Maine, Bill Cassidy of Louisiana, Ben Sasse of Nebraska, and Rob Portman of Ohio.

Several senators did not even vote, likely because theyd left town for Memorial Day weekend. The senators to miss the vote were: Marsha Blackburn (R-Tenn.), Roy Blunt (R-Mo.), Mike Braun (R-Ind.), Richard Burr (R-N.C.), Jim Inhofe (R-Okla.), Patty Murray (D-Wash.), James Risch (R-Idaho), Mike Rounds (R-S.D.), Richard Shelby (R-Ala.), Kyrsten Sinema (D-Ariz.) and Pat Toomey (R-Pa.).

A Toomey spokesperson told HuffPost the senator had to attend to a family commitment but would have voted in favor of the motion to proceed to the January 6th commission legislation with the expectation that the Senate would consider, and Senator Toomey would have supported, an amendment that addresses Republican concerns about partisan staffing and the duration of the commission.

Before the vote, many Republicans insisted a commission was unnecessary, although there are lingering questions about the attack .

The role of the former president has already been litigated exhaustively in the high-profile impeachment trial several months ago, Senate Minority Leader Mitch McConnell (R-Ky.), who voted to acquit Trump in that trial, said before the vote. I do not believe the additional, extraneous commission that Democratic leaders want would uncover crucial new facts or promote healing. Frankly, I do not believe it is even designed to.

Congress routinely establishes advisory commissions in the wake of disasters or to make recommendations for difficult policy problems. A Capitol riot commission could offer an authoritative account of the day and answer lingering questions, including those about the ex-presidents response and why the National Guard didnt show up for hours.

But any new information a commission uncovers about the Jan. 6 riot would likely be inconvenient for a party that is still actively relying on Trump and his supporters to wrest back control of Congress in next years midterm elections. Republican voters still overwhelmingly support Trump and his policies despite what happened on Jan. 6; most believe he did nothing wrong.

Republicans also argue that congressional committees and the Justice Department are already deep into their investigations of what happened, but the same was true before Congress established a commission to investigate the Sept. 11, 2001, terrorist attacks. The bipartisan legislation Republicans filibustered Friday had been modeled on the bill setting up the 9/11 commission.

That is different in the sense of the magnitude of what occurred and the loss of life and that it was initiated from afar, Sen. Mike Braun (R-Ind.) said Thursday when asked if he believed the 9/11 commission was partisan in nature.

An amendment Collins offered to address her GOP colleagues concerns about the staffing of the commission failed to convince enough of the party to support the bill. Opponents claimed the commission would end up being partisan even though Democrats conceded to nearly all GOP demands in drafting the bill. The panel would have been equally divided among credible experts selected by both parties, with equal subpoena power.

Its even Steven. You pick one, I pick one, Murkowski said in advocating on behalf of establishing an independent commission.

Democrats have warned that without a full reckoning over the events of Jan. 6, its entirely possible they will happen again. Republicans across the country, after all, are codifying Trumps election fraud lies in new state laws that restrict voting.

My worry is that these groups are still out there, their grievances are still very real, the president continues to fuel them, Sen. Chris Murphy (D-Conn.) told HuffPost.

Sen. Josh Hawley (R-Mo.), the first senator who announced he would object to the election results based on voter fraud lies and a flimsy claim that Pennsylvania Republicans supposedly failed to follow their own state constitution by allowing too many mail-in ballots told HuffPost on Thursday hed be open to objecting again in 2024 if a Democrat wins.

It would depend on the circumstances, he said.

The GOP blockade over the Jan. 6 commission a measure with bipartisan support in both chambers of Congress will increase pressure on Democrats to go nuclear and eliminate the Senate filibuster, the institutions longstanding supermajority requirement for legislation.

With items that enjoy less bipartisan support on their agenda, like gun control and protecting voting rights, its only a matter of time before Democrats face a reckoning over the filibuster.

But Sen. Joe Manchin (D-W.Va.), a key holdout from a state Trump won in the 2020 election by nearly 40 points, insists hell never vote to kill the filibuster even after the fight over the Jan. 6 commission. He said after the vote Friday that he appreciated Republicans preserving the filibuster when Trump wanted it gone.

He beat on em, they didnt do it, so I respect that.

Manchin said he implored McConnell during a conversation on the Senate floor to let Republican senators vote their conscience. By Manchins estimate, 13 or 14 Republicans would have supported the bill if McConnell hadnt objected.

It was an awful lot of Republicans that would have supported it if it hadnt been for his personal intervention, Manchin said.

As for those Republicans, Manchin said they were driven by fear.

Im hoping they get the courage to come back and do it right, he said. Were not going to give up on this.