(Evan Vucci/Associated Press)

Donald Trump is not a strategic thinker. He’s impulsive and reactive, sometimes to his benefit, but often to his detriment. And right now, he’s reacting to his political troubles by lashing out at his own party in Congress. This doubtless makes him feel good — it’s obvious that he never feels more alive than when he’s fighting with somebody.

But it also poses a serious threat to his entire presidency. That’s because you could hardly come up with a better way to depress Republican turnout in the 2018 midterm elections than what he’s doing right now.

Philip Rucker, Sean Sullivan and Mike DeBonis describe the situation in today’s Post:

President Trump is strategically separating himself from Republicans in Congress, an extraordinary move to deflect blame if the GOP agenda continues to flounder.

Trump deepened the fissures in the party on Thursday when he accused the top two leaders on Capitol Hill of mismanaging a looming showdown over the nation’s borrowing authority. Republican lawmakers and aides responded to the president’s hostility with broadsides and warnings of their own.

Frustrated by months of relative inaction at the other end of Pennsylvania Avenue and emboldened by his urge to disrupt the status quo, Trump is testing whether his own political following will prove more potent and loyal than that of his party and its leaders in both houses of Congress.

It isn’t just Senate Majority Leader Mitch McConnell (R-Ky.) and House Speaker Paul D. Ryan (R-Wis.). Trump has also lashed out at Republican senators such as Jeff Flake of Arizona, against whom he’s actively promoting a primary challenge. This morning, Trump responded to some criticism by Sen. Bob Corker (R-Tenn.) by tweeting, “Strange statement by Bob Corker considering that he is constantly asking me whether or not he should run again in ’18. Tennessee not happy!”

The idea that Corker is “constantly asking” Trump anything is almost impossible to believe, because it’s not like they’re in daily communication and Corker is by all appearances possessed of some degree of dignity. (My guess is that they had one conversation in which Corker said that he was still deciding whether to run, and that’s what Trump is turning into him “constantly asking” whether he should run.) The point, though, is to cast Corker as a supplicant, an underling, an inferior, someone crawling on his knees to beg for Trump’s wisdom. If the president sees you as an adversary, even temporarily, he will do everything he can to belittle and humiliate you.

That’s how Trump operates, and he won’t change. Legislative failures will be greeted with attacks on his own party, because what’s important to him is that everyone knows it wasn’t his fault. When Republican politicians see his low approval ratings and try to distance themselves from him, he won’t do what previous presidents, both Republican and Democrat, have done in the same situation — gritted their teeth and accepted it as a manifestation of the primacy of self-interest for every politician — but instead will strike out angrily at them.

So consider the dynamic he’s setting in motion. If he thinks that his following is more potent and loyal than that of his party and its leaders in Congress, he’s almost certainly right. But that’s just the problem.

The most important fact to keep in mind is that Trump will not be on the ballot in 2018, but Republican members of Congress will. When he fights with them, he not only diminishes them, he hurts their image among precisely the voters they need the most: loyal Trump supporters. Midterm elections are won and lost on turnout, and Trump’s base is what stands between the GOP and disaster.

Yet Trump is discouraging them from feeling invested in the 2018 election. He’s promoting primary challenges (explicitly and implicitly) against members not because they’re insufficiently conservative, as was the case with tea party challenges during the Obama years, but because they’re insufficiently loyal to Donald Trump. Consider that in a recent GWU Battleground poll, 53 percent of Republicans who are represented by a Republican member of Congress said their member is not supportive enough of Trump. The president feeds that belief almost every day.

If there’s a rebellion of Trump loyalists against GOP members of Congress, it won’t have nearly the power of the tea party, and it probably won’t strike the same terror into the hearts of Republican members. But it doesn’t have to. If Trump is telling everyone that the Republican Congress is a bunch of losers and you’re a loyal Trump voter, might you be a little less likely to turn out to vote in 2018 to support one of those losers? If there’s a primary challenge from a candidate running on a platform of supporting Trump and the incumbent beats it back, doesn’t that discourage you a bit more from getting to the polls to help that incumbent in the general election?

Global Opinions editor Karen Attiah deconstructs the Democratic Party's "Better Deal" platform, which she says will get it knocked out of future elections by ignoring minorities and marginalized groups. (Gillian Brockell,Kate Woodsome,Karen Attiah/The Washington Post)

So while Democrats will be getting their voters to the polls with the message that Trump must be stopped, the person with the country’s loudest megaphone will be telling Republican voters that their own members of Congress are barely worth supporting. The effect that produces may not be enormous, and most Republican members come from safe districts, but even a marginal impact could make a difference.

While things could certainly change over the next year, it’s looking like we could be headed for a wave election in which Democrats do extremely well. But control of the House will be very tight because of the GOP’s built-in advantage, a product of both gerrymandering and geographic distribution of both parties’ voters. Yesterday, Decision Desk HQ released a forecast showing Democrats winning 54 percent of the national House vote, but Republicans winning 53 percent of the seats and retaining the majority (much like what happened in 2012, when Democrats won more votes but Republicans held on to control). The wave could be big enough to overcome that GOP advantage, but it will almost certainly be close, which means that if Trump’s fights with Congress cost his party even a couple of seats, that could determine who controls the House.

All of this is happening because Trump is so relentlessly self-centered that he can’t grasp the idea that even if Republicans in Congress are getting on his nerves, he’ll only hurt himself if he helps them fail. And if he thinks he’s having a hard time now, just imagine what it would be like if Democrats controlled the House and they had the ability to stop every piece of legislation that Republicans propose — not to mention subpoena power. Then we’ll really see what Trump is like when he’s mad.