Democrats and voting rights groups scrambled Monday to figure out their next move after a key senator’s opposition seemed to doom a sweeping election overhaul bill and raise the prospect that no voting legislation would pass Congress amid what experts say is the greatest attack on voting rights in generations.

Sen. Joe Manchin’s op-ed in a newspaper in his native West Virginia on Sunday regarding HR1 effectively neutralized his party’s main weapon against a wave of Republican-backed laws tightening access to the ballot in numerous states. It left Democrats and voting rights groups grasping for an alternative.

Some said they’d follow Manchin’s suggestions and prioritize a narrower piece of legislation known as HR4 that updates the Voting Rights Act to once again require federal approval of new voting laws and legislative districts in certain states. Others said they wanted to increase the pressure on Manchin, who is scheduled to meet with civil rights leaders Tuesday. Still others insisted that Democrats needed to bring HR1 to the Senate floor later this month, as the chamber’s leadership planned to do before Manchin’s op-ed.

“It’s going to get messy,” said Fred Wertheimer, the president of the good-government organization Democracy 21 who helped draft HR1 in 2017. “What Manchin said is not the final word, as far as we’re concerned. I don’t believe he is prepared to go down in history as the senator that denied millions of eligible citizens, and in particular people of color, the opportunity to vote.”