Until their fourth debate last week, Republican presidential primary candidates had been notable for their apparent indifference to the Affordable Care Act. This was less a function of resignation than of repetition and fatigue. Nearly everyone in the Republican Party had demonstrated obeisance to the gods of Obamacare hatred, and every candidate had pledged to repeal the law; in light of this unanimity, it had become redundant to waste precious airtime kicking it around. Marco Rubio, Jeb Bush, and erstwhile candidate Scott Walker had each introduced substantially similar Obamacare replacement plans, and for a time, it was fair to say that a consensus was congealing. The real debate wasn’t about which candidate was most contemptuous of Obamacare, but about how to fill the void after its repeal.

That all changed in last Tuesday’s debate, when the candidates, faced with pliant moderators, rejoined the competition to be the most avowedly anti-Obamacare Republican in America. Though Obamacare significantly increases worker leverage, Rubio cited repealing it as one of “the best way[s] to raise wages.” Carly Fiorina said, “Obamacare has to be repealed because it’s failing the very people it was intended to help,” later adding that the law “isn’t helping anyone” and is “crushing small businesses.” Donald Trump promised that Obamacare “will be repealed.”

Nobody, including the three senators in the race, betrayed any awareness of the fact that Republicans in Congress are in the midst of their most concerted effort in four years to place a repeal bill on President Obama’s desk—and struggling mightily. 

It’s hard to imagine a more fitting testament to the gulf between the demands of Republican primary voters, who have incredible sway over presidential candidates’ rhetoric, and political reality in the broader electorate, which has more direct influence on congressional outcomes. The fact that a Republican Congress is too paralyzed to pass legislation addressing the right’s most pressing grievance is a coal-mine canary that should alarm both Republican congressional leaders and the candidates who’ve been busy shaping their 2017 workload with promises that extend beyond Obamacare into even thornier terrain. 

Obamacare repeal brings the rubber of conservative absolutism into contact with the road of practical reality. About 16 million previously uninsured people now have health insurance thanks to the Affordable Care Act, and many Republicans, even very conservative ones, have awakened to the fact that they won’t be greeted as liberators if they rescind that coverage. Pace Fiorina, the law isn’t helping no one. It’s helping millions.

But health care isn’t the only realm of public policy where Republicans are making impracticable or politically toxic promises. The same tendency obtains in sweeping proposed overhauls of tax policy, financial regulation, immigration, climate change, reproductive rights, and foreign affairs. Moreover, this isn’t a quirk peculiar to pandering outsiders like Fiorina, Trump, and Ben Carson. It defines the entire field.

When Jeb Bush promises to “repeal every [regulation] that Barack Obama has,” or Trump promises to force Mexico to pay for a wall along the southern border, or Ted Cruz promises a flat tax, or everyone in the field pledges to turn incredulousness about climate change into national policy, they are narrowing their paths to the White House, yes, but they are also making a hash of their own potential presidencies.

A consolidated Republican government would both swing the pendulum of national policy way back to the right, but would simultaneously fall far short of being able to fulfill the candidates’ most ambitious proposals. That’s why their current Obamacare predicament is so instructive. 

Some of the GOP’s difficulty passing Obamacare repeal legislation is endemic to the Senate. Filibuster rules allow Democrats to insist that modifications to the health law require 60 votes to pass, leaving Republicans to choose between changing the rules unilaterally or squeezing repeal legislation through complex and constrained processes.

To circumvent the filibuster, Senate Republicans have decided to use a majority-vote procedure designed to help Congress turn their fiscal blueprints for the country into law. This process, known as budget reconciliation, is a powerful tool for creating, eliminating, or changing tax-and-spending programs, but it is limited to those programs. The Affordable Care Act, by contrast, is a hodgepodge of taxes, subsidies, and regulations, the latter of which is immune from the reconciliation process. Senate Republicans are thus barred from repealing the law’s coverage guarantee, and, crucially its individual mandate, without a supermajority.

This complication alone threatens to derail the repeal initiative. Conservatives in both the House and Senate say they are loath to support partial repeal legislation, and in the House, where rules are laxer, Republicans passed a reconciliation bill that eliminates the individual mandate. When it comes time to iron out the differences between House and Senate proposals, conservatives might decide that the necessary concessions weaken the legislation into pointlessness.

But the bigger problem is that Republicans in both chambers are losing their nerve. They could theoretically pass legislation to zero out the law’s subsidies and Medicaid expansion through the budget process, but they don’t want to answer to their voters for doing so.

“I am very concerned about the 160,000 people who had Medicaid expansion in my state. I have difficulty with that being included,” West Virginia Senator Shelley Moore Capito told The HillAnother Republican senator chimed in anonymously, “Repealing the Medicaid expansion is not going to be in there because it’s too problematic for many Republicans.”

Neither the Senate’s nor the House’s bill targets the coverage expansion—the very entitlement that fuels the right’s outrage. And this for purely symbolic legislation! Actually replacing Obamacare will at this point—and at the very least—require Republicans to implement an alternative before phasing out the existing system.

Republican presidential candidates don’t yet have to grapple with the likelihood that the same squeamish members of Congress will be in office in 2017—and that even a concerted effort by a consolidated Republican government to repeal Obamacare is likely to collapse. But their shared tendency to make fantastical promises unrooted in reality has some Republican insiders deeply worried—not just about their electability, but about what happens if one of them is elected president.

In a remarkable confession to Robert Costa—who ascended to the Washington Post from the conservative National Review and is deeply sourced in Republican politics—a party strategist essentially acknowledged that Hillary Clinton is a safer presidential bet than either of the GOP’s front-running candidates, Trump and Ben Carson. “We’re potentially careening down this road of nominating somebody who frankly isn’t fit to be president in terms of the basic ability and temperament to do the job,” the strategist said. “It’s not just that it could be somebody Hillary could destroy electorally, but what if Hillary hits a banana peel and this person becomes president?”

This is indeed a spooky thought. Trump and Carson certainly do have the wrong temperament for the presidency. The fact that one of them could conceivably win it is a profound indictment of a party whose leaders have let the tiller slip, and it’s good that some Republican operatives are aware of it. Yet those same operatives seem completely unperturbed by the fact that their less impetuous candidates are courting failure in more mundane ways, overcommitting themselves such that whether they have a presidential temperament or not, the presidency will have the wrong temperament for them.