Trump retreats on the border wall.

Imagine if presidents had left more wiggle room in their most famous pronouncements: “One of the many things we have to fear is fear itself.”

“Read my lips — no new taxes, unless we really need them.”

“Mr. Gorbachev, tear down this wall if you feel like it, but if you don’t, that’s cool, too.”

This week capped the slow motion rollback of President Donald Trump’s most forceful campaign promise — that not only was he going to build a wall between the U.S. and Mexico, Mexico was going to Venmo him the money to pay for it. Going to a Trump rally without hearing this boast would be like going to a Flock of Seagulls show and not hearing “I Ran (So Far Away).” It was literally his greatest hit, complete with his crowds joyously singing along.

Yet campaigns are a work of fiction and governing is an exercise in fact. At a campaign rally this week, Trump threatened a government shutdown unless Congress provides funding for a border wall. “One way or the other, we’re going to get that wall,” he told supporters in Arizona.

Of course, his new promise to build the wall is missing the most glaring provision of his campaign proposal. By threatening a shutdown, he is ordering Congress to pump $1.6 billion (as just a down payment) into a border wall that is, according to a February poll by the Pew Research Center, opposed by 62% of American citizens. Even Speaker of the House Paul Ryan, who has been slow to criticize Trump on other matters, scoffed at the idea of shutting the government down to fund a wall.

It was clear there was never going to be a full wall built on the border, and it was even clearer that Mexico was never going to fork over a single peso to help in the effort. At its most, the wall was a symbol, showing that Trump was a tough guy.

But his attempt to tie wall funding to a government shutdown is simply more evidence of Trump’s fecklessness. While he brags endlessly about his ability to forge “the best deals,” he is essentially taking the wall issue and putting it on Congress’ doorstep so he can blame Ryan and Senate Majority Leader Mitch McConnell when it doesn’t happen.

It was clear Trump never realistically expected Mexico to chip in for any sort of border enforcement. During a Jan. 27 phone call with Mexican President Enrique Peña Nieto, Trump begged the Mexican president to stop telling the press that his country would never pay, as Trump knew it put him in a rhetorical jail from which he couldn’t escape. Trump all but conceded that the wall was a campaign ruse when he told Peña Nieto it was “the least important thing we are talking about, but politically this might be the most important.”

“The main problem in any democracy,” wrote Hunter S. Thompson in “Fear and Loathing on the Campaign Trail ‘72,” “is that crowd-pleasers are generally brainless swine who can go out on a stage & whup their supporters into an orgiastic frenzy — then go back to the office & sell every one of the poor bastards down the tube for a nickel a piece.”

Clearly, Trump’s supporters aren’t picking over the minute details of various tax plans —they will stick with him as long as, in the words of Sarah Palin, left-wing “splodey heads keep splodin’.”

Yet perhaps when team #MAGA sees there’s no wall, Obamacare remains unmolested, and Trump can’t shepherd through meaningful tax reform, they’ll realize they’ve been sold down the tube. Perhaps they can then take their nickels and buy Tshirts that say, “I voted for Trump and all I got was some Confederate statues removed.”