During the 2016 presidential campaign, many Republicans looked at Donald Trump and saw a president who would preside over a wave of ambitious conservative legislation. Sure he was no ideologue, and had only the barest understanding of any policy issue. But that's what made for a terrific partnership between Congress and the White House: Paul Ryan and Mitch McConnell would pass the bills, and because Trump didn't care about the details, he'd sign whatever they put in front of him. What could go wrong?

Quite a bit, as it turns out.

With the GOP's first legislative priority — the repeal of the Affordable Care Act — a chaotic mess, there's a genuine possibility that at some point President Trump may just decide to cut his losses and walk away from what Republicans say is their most important legislative goal.

When President Trump said a couple of weeks ago that "nobody knew that health care could be so complicated," I suspect he wasn't talking only about his growing awareness of the issue. He may also have been grappling for the first time with the tradeoffs that reforming health care requires.

As a candidate his impulse ran toward promising the moon: Everyone will be covered, the care will be terrific, it'll all cost less than it does now. But once you have to write legislation, you realize that you can't have everything. If you want to cover more people, for instance, it's going to cost money.

If you want to protect the tens of millions of Americans with pre-existing conditions, well that costs money too. If you want to push people off government programs and into private insurance, you may not like the decisions private companies make to maintain their profits. How do you balance everyone's competing goals? There are no perfect answers.

And the bill Paul Ryan came up with has proven to be a disaster, hated not only by Democrats but by many Republicans as well, for a set of reasons that make a compromise hard to imagine. More centrist Republicans in the Senate don't like how it hurts people in their states, particularly the poor and middle class. Conservatives in the House wish it were even more cruel. How do you reconcile those objections? Chances are you can't.

But Trump still wants to satisfy everyone. Consider this exchange from a Wednesday interview he did with Tucker Carlson of Fox News:

CARLSON: This bill has, as one of its centerpieces, a tax cut for investors that would primarily benefit people making over $250,000 a year. Already done pretty well in the past 10 years, as you know. A Bloomberg analysis showed that counties that voted for you, middle-class and working-class counties, would do far less well under this bill than the counties that voted for Hillary, the more affluent counties.

TRUMP: Oh, I know. I know.

CARLSON: It seems like —

TRUMP: It's very preliminary, Tucker.

CARLSON: — maybe this isn't consistent with the message of the last election.

TRUMP: No. A lot of things aren't consistent. But these are going to be negotiated.

Trump says, "Oh, I know. I know," but he offers no insight at all into how he would resolve the conflicts that repeal presents. For instance, is he willing to see millions pushed off their insurance in order to realize the conservative goal of gutting Medicaid? We don't yet know, but he seems to still be holding out hope for a fantasy bill that will make everyone happy.

But in the end, Trump's highest priority will inevitably be his own popularity. If there comes a moment when he feels like he's being dragged down by the repeal effort and there's no way to turn it around, he'll be willing to pull the plug.

If he does, what would happen from that point is unclear. Republicans would probably try to change the ACA piece by piece, with a series of bills amending specific provisions of the law. They'd still consider the defeat of the larger repeal bill to be a disaster, a betrayal of the promise they've made so many times to their base. Which it would be.

And if it threatened their ability to hold on to Congress in 2018? I'd suggest that Trump wouldn't be entirely heartbroken if the Democrats took back one of the houses of Congress. Then he wouldn't have to bother with legislating — which is so boring and complicated — and could just concentrate on executive actions where he can make bold moves without having to persuade 218 House members and 50 senators to go along.

The longer the health-care issue drags on, the more impatient he's likely to get. Republicans in Congress may feel that repealing the ACA is an absolute requirement for them, but Trump isn't nearly as invested in it. So there could come a point where abandoning the effort looks like the best of the available options — for him, anyway. Which is ultimately what he cares about most.