Washington • President Trump’s “big, beautiful wall” was never a serious policy proposal. It was a symbol to reassure his supporters that he would keep the sorts of people they don’t like out of the country. It was also a memory device designed by his advisers to remind Trump to talk about immigration in every 2016 campaign speech.

But since Trump has absolutely no interest in policy, it is appropriate that he has shut down part of our government to defend a piece of rhetoric.

He didn’t even intend to do this. Late last year, he signaled to Republican Senate Majority Leader Mitch McConnell that he’d sign a bill to keep the government open and McConnell dutifully got it through the Senate unanimously.

Trump closed a quarter of the government ("I will take the mantle of shutting it down," he said in December) only after right-wing commentators told him they would be very mad if he relented on The Wall. Thus did a chief executive who likes us to think he's strong cower before a few ideologues who have only microphones and pixels as their weapons.

This is the context of the useless, genuinely stupid fight we are in. It's why the president's speech to the nation on Tuesday night was so empty, so unpersuasive to anyone but the already committed.

Trump now loves this shutdown because it does four things for him:

It makes him the center of attention.

It tells his base that he is willing to stand up for the idol they adore.

It pushes aside inconvenient news — about the Russia probe, about the administration’s flipping and flopping on Syria, about the many administration posts that are empty.

And it creates the appearance that he is doing something when, in fact, he is doing nothing at all, except keeping large numbers of federal employees from carrying on and earning a living.

Trump's phony "crisis" talk means he may have to call his own bluff. This is why there is a good chance he will invoke emergency powers to force the military to build the wall. The move would perfectly sum up his approach to government: It would look dramatic and "strong," it would waste federal funds for self-aggrandizing reasons, and it would be an abuse of his authority, since the "emergency" in question is not an emergency at all.

The only intelligible rationale behind Trump's shutdown is Richard Nixon's old "madman theory." The idea is that if one party to a negotiation behaves in a particularly crazy and dangerous way, the more reasonable people at the table will give in simply to end the lunacy and avoid catastrophe.

Already, sane voices are proffering compromises — for example, to give Trump some wall money in exchange for protecting the Dreamers, undocumented immigrants brought to the United States by their parents when they were young.

The problem is that Trump has repeatedly rejected deals on the Deferred Action for Childhood Arrivals program. And the same anti-immigrant voices who pushed Trump to shutter the government have put him on notice that they would see concessions of this sort as a sell-out.

Right wing commentator Ann Coulter tweeted her spleen Sunday by referring to Jared Kushner, Trump's son-in-law thought to be interested in a deal, and Neville Chamberlain, the British prime minister famous for appeasing Hitler: "If Kushner (Trump) trades amnesty for a wall, history books will have to be pulled from the shelves to replace 'Neville Chamberlain' with 'Donald Trump.'"

Trump is willing to keep hundreds of thousands of government workers idle and unpaid. He lacks the guts to stand up to Coulter and her allies.

Which means that the only path forward is for sensible souls to pressure McConnell and other Senate Republicans to stop enabling the blusterer-in-chief and put bills on Trump's desk to reopen the government. Already, at least three Republican senators (with others titling that way) have said it's time to do this. More should join them.

On Fox News after Trump's speech, Sen. Lindsey Graham, R-S.C., warned that if Republicans "undercut the president, that's the end of his presidency and the end of our party."

Graham was at best half-right. Yes, Republicans might humiliate Trump by forcing him to acknowledge that this whole business is a fool's errand. But in doing so, they would be taking a step toward rehabilitating a party that has regularly abetted the depredations of a man who cares only about the spotlight and a totem he claimed Mexico, not American taxpayers, would finance.

E.J. Dionne