Republicans are learning the ultimate lesson in policy-making: Overhauling the American health care system is a nearly impossible task.

Now comes an equally tricky part: contending with a disaffected, mad-as-hell base of supporters who expected them to follow through on a seven-year promise to repeal and replace Obamacare.

That’s the reality the party is confronting after Senate Majority Leader Mitch McConnell’s (R-KY) slim hopes of passing a reform package came crashing down once again on Monday when two conservative senators, Mike Lee of Utah and Jerry Moran of Kansas, announced they would vote against a procedural motion on the legislation.

McConnell now faces one of the most difficult obstacles of his decades-long career. His close aides fret that failure to pass some legislation could depress the Republican base and leave the party incredibly vulnerable in 2018. But no amount of procedural maneuvering or policy reshuffling has allowed him to crack the health care reform code. His options are limited and none are particularly confidence-inducing.

On Monday, McConnell announced that he would allow a vote on a proposal to repeal Obamacare immediately with a two-year window to come up with a replacement. It was a strategic gambit, designed to keep the raucous base at bay. Republican lawmakers voted in 2015 in favor of this approach. But they were assured then that President Obama would veto their effort, and in the current climate there is no guarantee—and, indeed, much doubt—that 50 members will say yes to this proposal.

Should that fail, McConnell could simply start over on Republican-authored reform. There are ideas out there. Most recently, Sens. Lindsey Graham (R-SC) and Bill Cassidy (R-LA) pitched a plan to send money to individual states and allow them to address their health care needs. But on Capitol Hill, their proposal has scant resonance.

Moreover, going this route risks the one commodity that McConnell doesn’t have: time. The majority leader wants to get health care out of the way as soon as possible in order to move on to other legislative priorities, notably tax reform. Hitting the reset button now means months more of negotiations.

Another option for Senate Republicans is to bring Democrats to the table—something that Senate Minority Leader Chuck Schumer (D-NY) has barred his members from doing so long as Republicans have continued to push for a repeal of Obamacare. Last week, two Democratic senators told The Daily Beast that they have had preliminary conversations with some of their Republican counterparts about ways to fix the Affordable Care Act. They expect those talks to pick up once the GOP accepts the law’s future in the immediate term.

“I think there’s a whole lot of interest in getting this right… and the way to do that is to actually slow down the process and go regular order,” Sen. Tom Carper (D-DE) told The Daily Beast, suggesting that lawmakers should hold hearings, vote on specific amendments, and attempt to craft a bill with 60-plus votes.

Before Monday night, Sen. Susan Collins (R-ME)—one of the loudest critics of the bill’s steep spending caps on Medicaid—was the only Republican calling for negotiations with Democrats. But shortly after Moran and Lee announced their opposition, Sen. John McCain (R-AZ), whose unexpected surgery last week caused McConnell to delay consideration of the bill, said in a statement that the Senate should return to regular order and move away from the current strategy of shutting out the minority party.

“The Congress must now return to regular order, hold hearings, receive input from members of both parties, and heed the recommendations of our nation’s governors so that we can produce a bill that finally provides Americans with access to quality and affordable health care,” McCain said, echoing Schumer’s calls for any legislation to be publicly debated.

This approach, however, may be more of a pipedream than the current one. McConnell has warned Republicans that he might have to work with Democrats on fixes if his own party can’t come together. But those Republicans don’t seem particularly interested in playing along. Asked, for instance, if he’d be open to holding hearings on the GOP bill, Sen. Pat Toomey (R-PA) told The Daily Beast that they were unnecessary.

“I don’t think there’s any need for that when the bill is public,” he said. “It’s available to everyone to see, as people have not been shy about commenting on it.”

The wild card for McConnell, in the end, is not Schumer or his own party. It’s President Trump.

Though he has been largely disconnected from the issue, Trump has gravitated toward the concept McConnell now endorses: repealing Obamacare now and replacing it at an unspecified later date. He first floated the idea more than two weeks ago.

“Republicans should just REPEAL failing ObamaCare now & work on a new Healthcare Plan that will start from a clean slate. Dems will join in!” he wrote on Twitter on Monday night shortly after Lee and Moran announced their opposition.

Trump also has spoken about letting the law fail, so as to bring Democrats to the negotiating table. Whether his administration follows through on that threat—and it has a fair amount of operational control over the law to do so—could very well determine McConnell’s hand.

Either way, McConnell will have to make some tough choices in the days ahead, and he will have to do so knowing that the blowback will be on his members—not the president.

“I think Trump supporters will feel that they have been betrayed by politicians who say one thing and then do something completely opposite to what they have said,” said John Feehery, a longtime Republican operative. “I don't think they will blame Trump for this. I think they will blame the senators who have not kept their promises.”