Four Republican members of the House of Representatives defied their party’s leadership to join Democrats in forcing a vote on a bill to extend subsidies for the Affordable Care Act, which are set to expire at the end of this year unless Congress acts to renew them.

The surprising breaking of ranks within the GOP comes after weeks of heated debate within the party over what to do about health care, as more than 20 million Americans will face skyrocketing premiums if the subsidies are allowed to lapse.

House Speaker Mike Johnson said earlier this week that those negotiations ended without enough progress to hold a vote on extending the subsidies. That announcement ultimately led the four Republicans to sign a discharge petition created by Democrats, giving that petition the 218 votes needed to force a vote on a Democratic proposal to extend the subsidies for three years.

“Doing nothing is not an answer,” GOP Rep. Mike Lawler of New York told reporters Wednesday after signing the petition. “I didn’t come here to be a potted plant. I came here to actually do stuff to help my constituents.”

Despite the success of the petition, the fate of the subsidies is still very uncertain. The House will eventually hold a vote on extending them, but it’s possible that the vote could fail if even a single signee can be convinced to oppose it. If the bill does pass the House, it would still need to be approved by the Senate, where an identical Democratic proposal was rejected in a party-line vote last week.

What happens next

Under official House procedures, a successful discharge petition is subject to a “layover” period,  meaning Johnson wouldn’t be required to allow the vote until Congress reconvenes early next year — after the subsidies will have already expired. Johnson could choose to hold the vote at any time, however. Democrats pressed him on Wednesday to allow the vote to happen immediately, arguing that there was no reason to allow the subsidies to lapse over arcane legislative rules.

“Under no circumstances should we leave this capital this week before voting on an extension of the Affordable Care Act tax credits bill that we know will pass,” House Minority Leader Hakeem Jeffries, who launched the discharge petition in November, said on the House floor Wednesday.

Johnson hasn’t given any indication that he’ll concede to the pressure and allow a vote before he’s formally obligated to. If he holds firm, the earliest a vote could be held is in early January after the House reconvenes following the holiday break.

A majority of House members signed the petition, which suggests the subsidy extension has a strong chance of passing once it eventually makes it to the floor. The proposal’s prospects in the Senate are murky at best.

Republican Senate Majority Leader John Thune was noncommittal on Wednesday when asked whether he would allow a vote on the subsidies if the House bill eventually passes.

“We’ll cross that bridge when we come to it,” he told reporters.

The Senate has already considered — and rejected — Democrats’ proposal. Thune allowed a vote on a three-year extension for the subsidies last week, fulfilling a promise he made last month as part of the agreement to end the government shutdown. A majority of senators voted in favor of the bill, but it came up well short of the 60-vote threshold needed to clear the filibuster. Any future votes on the subsidies would also need 60 votes to pass.

Regardless of what happens with that specific plan, the success of the discharge petition could prove to be a key turning point for negotiations around alternative proposals to save the subsidies. A group of moderate members of Congress reportedly met behind closed doors on Wednesday to discuss how they might use the petition as a vehicle for bringing up a compromise bill that would extend the subsidies, but make them less generous by adding new income limits or minimum out-of-pocket costs.

“I think it’s important that the House and the Senate figure out a way that we can avoid this cliff,” Republican Sen. Lisa Murkowski of Alaska said Wednesday. “And an extension is what we’re gonna be doing.”

Barring an unexpected vote in the House before the legislative year ends on Thursday, those conversations will continue over the holiday break and the future of the Affordable Care Act will remain in limbo until Congress returns to Capitol Hill early next month.