Supporters of the Affordable Care Act have been emboldened recently by several developments that suggest repealing the health care law could inspire a tremendous backlash and spook Republicans in Washington, who are badly at odds with one another, into full retreat.

President-elect Donald Trump, who previously undermined congressional repeal efforts by insisting that Republicans replace and repeal the law simultaneously, pledged on Saturday the replacement would provide “insurance for everybody.” That same day, Representative Mike Coffman of Colorado became a symbol of GOP jitters when he sneaked away from a regular constituent meeting that was overrun with people alarmed by the repeal effort. And on Tuesday morning, a Congressional Budget Office analysis found that the GOP’s repeal legislation would strip insurance from 18 million people in one year, and deny insurance to millions more over the ensuing decade.

The repeal push is uniting liberals and dividing conservatives, leaving supporters hopeful that their efforts to save the law might ultimately prevail. Stopping repeal requires only three GOP defections, and even if Republicans pass legislation that sunsets the Affordable Care Act in the coming years, the law’s supporters will still have time to rescue key elements of it, if not the whole thing.

These encouraging signs are fueling liberal activism; it’s possible to imagine a Tea Party–like resistance forming on the left and making Republicans pay a political price for threatening their constituents’ health care. But as they rack up near-term victories, Obamacare supporters should think ahead to what the fight will look like in the coming weeks and months. The moral of the Tea Party story is that Democrats knew they’d pay a price for passing Obamacare—but they passed it nevertheless. The momentum of the past several days could easily dissipate or reverse itself, and liberals should be prepared to act if and when it does.

Republicans are clearly scared of the political risks of defunding Obamacare. Try as they might to blame Democrats, they even seem to realize that once they change the law in any significant way, they will own the consequences. This is why, for instance, Republicans have agreed to throw money at insurance companies during an Obamacare phaseout period to keep them from fleeing the market. It’s why Senators Susan Collins of Maine and Bill Cassidy of Louisiana want to punt the question of Obamacare repeal to individual states.