Donald Trump speaks at a campaign rally last month at Rimrock Auto Arena in Billings, Mont. (Brennan Linsley/Associated Press)

Republicans intent on rallying around Donald Trump are falling prey to self-delusion. The logical errors and inconsistencies are piling up.

1. Trump either will change his ludicrous proposals or Congress will stop him from going overboard. (A tax plan to widen the debt by $10 trillion? Don’t worry — Congress won’t pass it!) That assumes Republicans will actually stand up to Trump, a dubious proposition given that they won’t do so now. And it assumes that Trump won’t act in defiance of the courts and Congress. The courts and Congress certainly cannot stop him from rattling allies (which he has already done), buddying up to Russian President Vladimir Putin or ordering the armed services to commit war crimes. And if the courts and Congress really had the power to defuse every presidential misstep, then why not elect Hillary Clinton? After all, the courts and Congress would be there to check her as well.

2. If he changes policies, Trump will be fine. This is akin to saying President Obama’s only problem was liberalism. Trump’s policies not only are dangerous but also are evidence of a deliberate ignorance and moral vapidity. Do we imagine that Trump will suddenly realize everything he has been saying is daft? It is ironic that many of Obama’s qualities, which Republicans have railed against over the past seven years, would be even more problematic with Trump. They say Obama has been divisive, arrogant, surrounded by yes men, prone to using the instruments of executive power for political ends, delusional about the state of the world and economically illiterate. Trump, we would argue, is as bad as — or worse than — Obama on each count.

3. Trump knows he needs to be more “presidential.” There is no chance of that happening anytime soon. As The Post reported, many Republicans “are concerned about repeated comments singling out people for criticism on the basis of race, ethnicity or religion. … Many Republicans are also unnerved by Trump’s decision to continue picking fights with fellow Republicans and to spend time and resources campaigning in California and other Democratic-leaning states that he is extremely unlikely to win in November.” Maybe they should have thought about all that before endorsing him.

4. Republicans in the future can disown Trump. Lanhee Chen, a conservative policy wonk who has worked on a number of presidential campaigns, remarked on “Meet the Press”: “I mean I think, at some point, the Republican Party has to begin to look past just one election. And it seems to me that this sort of focus on a single election and winning a single election is one thing. But we’re only thinking about where is the party headed? What does rhetoric like this do to a party that, in 2012, after the 2012 elections, that tried to assess how successful they could be with minority voters.”

5. Trump will get smart advisers. We are still waiting for them to show up during his campaign. Once gaining office, presidents tend to retreat into an ever-shrinking cocoon of political loyalists whose judgment and policy expertise are questionable. If Trump is starting with Corey Lewandowski, Paul Manafort and a crop of foreign-policy cranks, imagine how dreadful things will be a few years into his term. Given how erratic and toxic Trump’s views are, it is hard to imagine too many deft policy hands joining his administration. (If they did, many may find themselves compelled to resign in short order.)

6. There is no other choice for Republicans. Well, the “Hail Mary” candidacy of National Review writer David French predictably did not get off the ground. But convention delegates have the power to demand that Trump release his tax returns. One of the better-known Republicans, Mitt Romney, for example, can change his mind and decide to run again. Republicans can vote for the Libertarian ticket. They can leave the top of the ticket blank. What is, however, becoming obvious is that the worst choice — one that leads to intellectual incoherence, mockery, denigration of character as a standard for elected office and personal embarrassment — is joining the herd to back Trump. Trump will eventually fade from the scene, but the stain of supporting him will last a lifetime.

In sum, many Republicans are convincing themselves that this election is the most important election ever, that no future election will be as consequential and that failure to put a Republican (no matter how awful) in the White House would be the ruin of the republic. That simply is not true, even with one Supreme Court seat open. (After 2020, maybe more will be open, which might be filled by a GOP president, if the party endures.) There are plenty of things worse than four years of Clinton with a GOP majority in one or both houses or a generation. One would be Trump in the White House. Another would be converting the GOP into a European-style National Front party.