(Reuters/Carlos Barria)

Now that Donald Trump has nearly secured the GOP presidential nomination, Republicans everywhere have to start thinking seriously about how they’re going to deal with him and how having him as their party’s leader affects their own plans for the future. And here’s the basic challenge that will create for Republicans: How can they keep Trump from veering wildly from the straight and narrow path of conservatism?

It’s going to require constant work. For Republicans, the next six months will be a struggle to constrain Trump’s erratic impulses, and even if they’re mostly successful, it still might not diminish the damage Trump could to do the conservative project.

Some Republicans are already trying to downplay this challenge. Speaker of the House Paul Ryan, who is currently engaged in an effort to shape his party’s policy agenda for the next decade or two, said this morning that he and other Republicans who care about conservative ideology have nothing to worry about:

House Speaker Paul Ryan downplayed any conflict between his detailed policy proposals and those pushed by Donald Trump on Wednesday, hours after the front-runner sewed up five more states and marched ever closer to locking up his party’s nomination.

“The key for populism, Joe, as you well know because you practiced this, how do you take this populism and connect it to principle so that it’s populism tethered to good principles which give us good solutions, not unprincipled populism and that to me is our value added to this equation,” the Wisconsin Republican said in a segment on MSNBC’s “Morning Joe” Wednesday, referring to co-host Joe Scarborough’s time as a lawmaker representing Florida.

Though he did not mention Trump by name and has been magnanimous even in his policy criticisms of Trump in the past, Ryan signaled that no matter Republicans’ standard bearer in November, the party will be “comfortable” and unify around the platform that he is advocating in Congress.

He also described any differences with Trump and other candidates over Obamacare and tax reform as small obstacles, remarking that they share broader agreement on the issues.

It’s possible that Ryan could prove right about this. But the amount of vigilance that will be required from Republicans could itself prove a strain.

Perhaps the most important thing to understand about Trump’s relationship to the conservative policy agenda, and to any agenda at all, is that he just doesn’t care about policy in the least. He has some sincere opinions on some issues, but for the most part, not only has he never thought much about any policy issue one might present him with, there’s almost nothing he thinks about an issue that isn’t subject to revision.

That’s why we’ve seen a particular pattern repeat itself so often. Trump will get asked a question about an issue he obviously hasn’t considered before. He’ll give an answer that doesn’t line up with conservative orthodoxy, because he isn’t aware of precisely what conservative orthodoxy is. Then Republicans will get enraged, the controversy will blow up, and a day or two later — after he’s had a chance to learn what he’s supposed to say — he’ll come back and offer a revised version of his position.

This happened on abortion (where he said women should be punished for having abortions, then said they shouldn’t), on transgender people being forced by the government to use the wrong bathrooms (where he said they should use whatever bathrooms they want, then said the issue should be decided at the state and local level), and on Israel and the Palestinians (where he first said he wanted to be a neutral arbiter, then went to AIPAC and said “There is no moral equivalency” between Israel and the Palestinians).

That’s not to mention the positions on issues like abortion and guns that he changed before the race began. So if you’re a Republican, that’s about as much as you can hope for. He may not be with you already, but he’s responsive to pressure. Once you tell him that he has strayed, he comes back to the fold.

To be sure, whenever Trump comes out with a formal policy proposal, it’s right in line with conservative orthodoxy. So for instance, he has repeatedly said we should raise taxes on rich people, much to Republicans’ horror, but when he actually released a tax plan, it featured, guess what, a huge tax cut for the wealthy. The same thing happened on health care: he said some things suggesting there were parts of the Affordable Care Act he liked, but when he released his plan, it could have been lifted from the boilerplate on the issue you’ll find on any Republican candidate’s web site.

Today Trump is going to deliver an address on foreign policy, and while we don’t know what’s going to be in it, because this is a prepared speech — which means it was written for him by other people — I’m almost sure that there will be little if anything in there that Republicans will object to. It’ll talk about how Barack Obama is weak, our enemies don’t fear us, we need to increase military spending, we should tear up the Iran nuclear deal — all things ordinary Republicans say all the time.

This is all possible because, to repeat, Trump just doesn’t care about policy. That should make Republicans at least somewhat sanguine about what his presidency would be like. Paul Ryan can deliver him one bill after another written and passed by the GOP Congress, and Trump is likely to say, “Sure, whatever” and sign them.

And yet, there are some trouble spots for conservatives ahead, signaled by the areas where Trump has in fact gone against conservative orthodoxy. Trade is a big one — Trump seems to believe that if we increase tariffs on Chinese goods, then everyone in America will have a great job. There have been a few others, like his lack of enthusiasm for cutting Social Security. Then there’s his ban on Muslims entering the U.S., which (while Republican voters support it) GOP elites find vulgar and damaging to the party.

And so, in the general election, we may see examples of Republicans like Ryan struggling to pull Trump back into line: when his impulse takes him to a place that’s popular with the electorate, but it’s a place other Republicans don’t want to go. Then they’ll have a much harder time making the case to him that he needs to get back with the conservative program.

On the other hand, if Trump remains as dreadfully unpopular with the general electorate as he is now, and he goes down to a sweeping defeat, maybe Republicans would be better off if he proves to be an imperfect representative of GOP ideology. Though that may not be much comfort.