A coalition of progressive groups are upping the pressure on Senate Majority Leader Charles Schumer (D-N.Y.) to nix the 60-vote legislative filibuster after Republicans were able to successfully block a bill using the procedure for the first time this year.

More than 100 groups sent a letter on Thursday to Schumer arguing that in the wake of GOP senators blocking a bill to create a commission to probe the Jan. 6 Capitol attack, "it is clearer than ever that the filibuster needs to be eliminated."

"We call on you and the Senate Democratic caucus to eliminate the filibuster as a weapon that Sen. McConnell can use to block efforts to defend and strengthen our democracy and make our government work for the American people," the groups added in the letter, which was spearheaded by Fix Our Senate.

The letter, which was first reported by NBC News, cites frustration from Democrats — including directly quoting Sen. Joe Manchin (D-W.Va.), who is opposed to changing the Senate's rules — over the GOP filibuster of the commission legislation, as well as pointing to a looming filibuster fight over voting rules. 

Schumer has vowed to hold a vote on a sweeping bill to overhaul elections before the Senate leaves town at the end of the month. 

The bill has no support from Republicans, who compare it to a federal takeover of elections, and Manchin also isn't on board. But Democrats view the legislation as vital as Republican-led state legislators across the country introduce, debate and pass bills that would place new restrictions on voting access.

"Investigating an insurrection and protecting voting rights should not be controversial or partisan — and they should not be issues that a minority of senators are allowed to block," the groups wrote.

The Senate is poised for a brawl over the filibuster, with Schumer preparing to hold votes on the election bill and a separate paycheck proposal previously blocked by Republicans under the Obama administration. He's also mulling votes on LGBTQ equality and gun reforms, which without bipartisan deals would be all but guaranteed to fall short.

But progressives have an uphill fight to get Schumer and his caucus to change the Senate's legislative filibuster, which requires 60 votes to pass most bills.

Schumer hasn't explicitly come out in favor of gutting the filibuster but has argued that "everything is on the table" in order to enact a "bold" agenda.

And after Republicans blocked the Jan. 6 legislation and a handful slow-walked bipartisan China legislation, Schumer warned his caucus that "we have also seen the limits of bipartisanship and the resurgence of Republican obstructionism."

But to change or get rid of the legislative filibuster, Schumer needs total unity among his 50-member caucus.

Several Democrats are viewed as wary of gutting the filibuster, though some, like Sen. Angus King (I-Maine), have signaled they would be willing to do so if Republicans stonewall voting rights legislation.

But Manchin and Sen. Kyrsten Sinema (D-Ariz.) are vocally opposed to changing the rules and are showing no signs of budging after Republicans blocked the commission legislation last month.

Sinema sparked fierce fury from progressives when she defended the filibuster during a stop this week in Arizona with Sen. John Cornyn (R-Texas), who voted against the Jan. 6 bill. 

"To those who say that we must make a choice between the filibuster and 'X,' I say, this is a false choice. ... The way to fix that is to fix your behavior, not to eliminate the rules or change the rules, but to change the behavior," Sinema told reporters.