Joe Raedle/Getty Images (Joe Raedle/Getty Images)
Opinion writer

When presidents run for reelection, they often face an agenda problem. When you’re the challenger, things are easier: You can attack the status quo and promise a glittering future that benefits from being imaginary. But once you’ve been in office for a term, suffering the inevitable defeats and compromises that even the most successful presidents have to endure at least in some measure, you can’t be so aspirational.

You can say “stay the course” if everything’s going great, but if the picture is mixed or bad, that’s harder to do. And new proposals may be greeted with “If that’s such a great idea, how come you didn’t do it already?”

Which is why most presidents up for reelection run largely negative campaigns, saying, “I may not be perfect, but that guy would be a complete disaster.” It turns out to be an extremely effective strategy; in the past 100 years, the only presidents to lose their reelection bids were Herbert Hoover, Gerald Ford (who wasn’t elected in the first place), Jimmy Carter and George H.W. Bush.

Nevertheless, the incumbent still has to offer up a program of things he plans to do if he’s granted a second term. So when President Trump is on the campaign trail talking about his second term, what is he going to say?

I'm reminded of the 1996 episode of "The Simpsons" in which the retired Bush writes in his memoirs, "And since I'd achieved all my goals as president in one term, there was no need for a second. The end." Which will probably be how Trump tells the story if he should lose, but before then he has to lay out some kind of an agenda. Right now, he's caught between things he said he'd do but can't, and the things he's already done that he can't promise to do again.

For instance, where would Trump like to go on the economy? He already cut taxes for the wealthy and corporations, which turned out to be much less popular than Republicans hoped. Is he going to suggest more tax cuts? I’m sure Democrats would be only too happy to have him do so. He has turned over large swaths of the government to the corporations and special interests that are supposed to be regulated, so that’s done. The one area that interests him and where he could go further is trade, but after promising to get America’s manufacturing jobs back from overseas and starting a trade war with China, it’s unclear what new trade initiatives would be smashingly popular with the electorate.

How about health care, the key domestic policy issue that cost the GOP so much in 2018? Like most Republicans, Trump has no ideas about how to improve it, and if he promises again to try to repeal the Affordable Care Act, that too would be a gift to Democrats.

Climate change? Trump still thinks it’s a hoax, and is preparing to establish a panel to study it, led by a climate denier who has campaigned to stop the vicious maligning of innocent carbon dioxide. (I’m not kidding.)

How about transportation? Education? Child care? Trump doesn’t have any particular ideas, and though someone might write a few words about them for him to deliver in a speech, he’ll probably get bored and skip over those sections to rant about the media. Some of his advisers appear to want to start a war with Iran, but Trump doesn’t seem to share their zeal.

“More conservative judges” will certainly be on his agenda, and that will be a strong appeal to Republicans. But he will no longer benefit from the greater salience the courts used to have for the right than for the left. Indeed, with the next year and a half likely to bring any number of controversial rulings from the conservative majority on the Supreme Court on issues such as abortion and voting rights, if anything, the courts are likely to be an issue that motivates his opponents more than his supporters.

There is one issue that Trump cares deeply about: immigration. But as I’ve noted before, he is in a difficult spot for 2020 when it comes to his border wall, since he now wants to argue both that we need a wall to stop the hordes of criminal aliens coming to kill us all and that he already built the wall and it’s fantastic.

Congress is no help. In the 20 months between now and Election Day, the voters may all but forget that legislating is something that happens in America and that the president might be able to accomplish. With Democrats now in control of the House, Trump’s legislative agenda is essentially dead (not that he had all that much of a legislative agenda to begin with). Congress will pass some bills here and there on things the parties can agree on, such as the bill to address the opioid crisis Trump signed in October. But they won’t get that much attention or enable him to say that he has a slate of initiatives ready to go, especially since Democrats are likely to keep the House in 2020 (and have an outside chance of taking the Senate, too).

What does that leave Trump with? A purely negative campaign. Which, let’s be honest, he’d almost certainly run even if he had a long list of things he wanted to do. That’s not just his personal inclination, but also what he believes motivates his voters and leads to success. And it won’t just be negative; it’s likely to be the most vicious, underhanded, dishonest campaign any one of us has seen in our lifetimes.