Republicans in the US Senate again blocked a significant voting rights bill from advancing on Wednesday, a move many see as a breaking point in the push to get rid of the filibuster, the Senate rule that requires 60 votes to advance most legislation.

The bill – the John Lewis Voting Rights Advancement Act – is one of two major pieces of voting rights legislation Democrats are championing in Congress in an effort to fend off attempts across the US by Republicans to erode easy access to the vote. Those efforts often most affect communities of color.

The measure, approved by the US House in August, would have implemented a formula at the heart of the 1965 Voting Rights Act that required certain places, where there was repeated evidence of voting discrimination over the last 25 years, to get any voting changes pre-cleared by the federal government.

The US supreme court struck down a previous version of the formula in 2013, saying it was outdated, a widely criticized ruling that civil rights groups say opened the door to voting discrimination.

There was never any serious prospect of the bill passing – only one Republican senator, Lisa Murkowski, supported it. The vote in the Senate was 50-49 in favor of advancing the bill.

But Wednesday’s vote was targeted towards Senator Joe Manchin, the West Virginia Democrat who supports the filibuster, showing him that passing voting rights legislation is not possible while the filibuster remains in place.

Many Democrats hope it will be the final straw for Manchin and Kyrsten Sinema, an Arizona Democrat, who is also a staunch defender of the filibuster. Republicans have successfully filibustered voting rights bill three times already this year, including once just two weeks ago.

Chuck Schumer, the Senate majority leader, said Wednesday’s filibuster was a “low, low point in the history of this body”.

He continued to suggest Democrats would consider options for getting rid of the filibuster, saying they would “explore whatever path” was needed to restore the Senate to its status as a deliberative body. He said the gears of Congress’s upper chamber had “ossified” and that Democrats were committed to continuing to push forward on voting rights “even if it means going at it alone”.

Nineteen states enacted nearly three dozen laws that make it harder to vote between January and the end of September, according to a tally by the Brennan Center for Justice. While the John Lewis bill would not necessarily have blocked all of them, it would have required some states, including Florida, Georgia and Texas, to get their policies reviewed before they were implemented.

“For the fourth time this year, Republicans have filibustered federal voting rights legislation. Whether it’s the original version of the John Lewis Voting Rights Advancement Act, the substitute amendment backed by Senator Murkowski, or other good faith legislative efforts to forge compromise and deliver on federal voting rights legislation, it’s crystal clear that Senator Mitch McConnell and Senate Republicans will weaponize the filibuster to block progress,” said Eli Zupnik, a spokesman for Fix Our Senate, which supports getting rid of the filibuster. “Our question now to President Biden and Senate Democrats is this: what are you going to do about it?” .

There is increasing urgency for Democrats to pass both the John Lewis measure and the Freedom to Vote Act, the other major voting rights legislation that aims to outlaw excessive partisan gerrymandering and would require early voting, no-excuse mail-in voting, as well as automatic and same-day registration.

State lawmakers are quickly passing new electoral districts that weaken the votes of minority voters and are distorted to lock in partisan advantages for the next decade. Democrats are also largely expected to lose control of the US House of Representatives next November.

Democrats have already started to escalate the pressure.

Joe Biden gave a strong public endorsement of changing the rule last month for voting rights legislation “and maybe more”.

But it’s unclear whether Manchin and Sinema, who have largely stymied Democratic ambitions in Congress so far, will budge. Manchin has indicated he does not support a filibuster carve out for voting rights legislation.

Civil rights groups have been pressing Democrats for months to get rid of the filibuster to pass voting reforms, publicly voicing their frustration that the White House isn’t putting enough political muscle behind the issue. Dozens of activists, including the son of Martin Luther King Jr were arrested outside the White House demonstrating ahead of the vote on Wednesday.

“Don’t take the Black vote for granted. Don’t torpedo our democracy. Our future depends on the restoration of voting rights for all,” said Derrick Johnson, the president and CEO of the NAACP. “Those who made campaign promises to the Black community must use any means possible to ensure that this Congress gets it done. The urgency of this issue cannot be overstated. We are watching.”

“We have had moments of bipartisanship on voting rights in our nation’s history, but sadly, this is not one of them. The only way to protect the freedom to vote is to end the filibuster,” said Sean Eldridge, the president of Stand Up America, and one of the people arrested on Wednesday.

“The King family and civil rights leaders from across the country came to the White House today because President Biden has the largest soapbox on the planet, and we’re asking him to use it to protect voting rights before it’s too late.”