WASHINGTON ― Unable to make either Mexico or Congress pay for his promised border wall, President Donald Trump is on track to renege on his first and most prominent campaign promise yet again.

The House is scheduled to vote on a temporary government spending bill Wednesday that provides not so much as a dime for the wall ― and prohibits the Department of Homeland Security from starting one. The Senate already passed the bill 85-7, and Trump will have until Sunday to sign it to keep most federal government agencies from having to shut down at midnight.

“What part of ‘no wall’ are you having trouble understanding?” laughed Rick Wilson, a Republican consultant and a Trump critic since the start of his presidential candidacy in 2015. “It shouldn’t surprise anyone that Trump lied about this. He lies about everything. There was never going to be a wall.”

Mark Krikorian, director of the Center for Immigration Studies that wants to restrict immigration into the United States, said the quandary Trump faces over the wall is his own fault for making such a big deal about the need for the barrier rather than better border enforcement broadly.

“At some point, people are going to say: Okay, where’s the wall?” he said.

With critical congressional elections now just six weeks away, some Trump allies fear that his strongest supporters will stay home out of disgust over the wall issue. “He’s going to have to do something before the election,” said Sam Nunberg of Citizens of the American Republic, a group created by former top White House aide Steve Bannon.

Bannon has for months advocated a government shutdown over the lack of wall funding as a way to energize Trump’s base of voters. Nunberg suggested an executive order of some sort that makes it appear the administration is doing something to advance it. “He’s got to have a deliverable on this,” he said.

His base would literally believe that a bucket of dung was a bucket of ice cream if he told them it was. He’s going to do his rallies and claim the wall is already halfway built, and it’s 400 feet tall. And people will cheer and whoop. Rick Wilson, Republican political consultant

White House deputy press secretary Hogan Gidley on Tuesday criticized Democrats for opposing the wall: “Democrats do not want a single dime spent on securing the border, building a wall, or on any other safety measures because they want open borders and sanctuary cities.”

But Trump’s White House did not address why Trump failed to get the Republican-led chambers of Congress to include any money to construct a wall along the southern border. Trump famously promised the wall in his candidacy announcement speech and said he would force Mexico to pay for it. He repeated both promises hundreds of times over the course of his campaign.

As president, Trump has taken multiple positions about signing another spending bill that does not include wall money. In March, just before signing a $1.3 trillion package, Trump lashed out at the Republican-led Congress over the funding omission.

He tweeted that one reason is he was considering a veto of that funding measure was because “the BORDER WALL, which is desperately needed for our National Defense, is not fully funded.”

He posted that message just hours before he wound up signing the bill, anyway.

He explained he was doing so because of all the money going to the military, and then claimed his wall was also getting some funding. “We have $1.6 billion for the wall,” he said. “We’re going to be starting work, literally, on Monday.”

That assertion, however, was false. While there was $1.57 billion for border security “procurement, construction and improvements,” 98 percent of it could not be used to build any type of structure that wasn’t already in use by 2017. Only $38 million was set aside for “border barrier planning and design” ― but not construction.

Since then, at his campaign rallies, he has repeatedly vowed to shut down the government if Congress did not give him wall money. “We’re about to get really nasty over the wall. We’re either getting it or we’re shutting down government,” he said in August in Wilkes-Barre, Pennsylvania.

But earlier this month, Trump began signaling that he would be following the advice of congressional GOP leaders who desperately want to avoid a pre-election government shutdown. They told him to wait until December to fight for his wall because he would have more leverage then, Trump has said.

“We’ll do it right after the election where hopefully, frankly, it will be easy because we have more Republicans, not less,” he told Fox News just before a Sept. 6 rally in Billings, Montana.

“I have no idea what the logic is,” Krikorian said, arguing that exactly the opposite political dynamic will probably be true ― that Democrats and those Republicans who oppose building a wall will have far more leverage after the elections than they do now, particularly if Democrats retake the House in November and are only weeks away from gaining formal control in January’s new congressional session.

“What is he going to do in December if he doesn’t get his wall funding?” Krikorian asked. “What’s he going to do, shut the government down? I’m not sure what the thinking is.”

The details of the spending legislation Congress is currently working on will likely diminish Trump’s leverage even further. Agencies including Defense, Health and Human Services and Veterans Affairs will be funded through October 2019. Only about a third of the government would shut down if Trump refused to sign a new spending bill by Dec. 7 ― but that third would include DHS, which is charged with border security. The effect would be to hurt Border Patrol agents, Immigration and Customs Enforcement officers and others whom Trump frequently claims to support.

“Are the Democrats really going to cave because of that? I don’t think so,” Krikorian said.

The whole wall thing was a shtick. As long as they were applauding it, he was going to go keep repeating it. It’s just part of the concert lineup. Rick Tyler, Republican political consultant

Whether and how much Trump’s failure to deliver on the wall will matter in the coming midterms remains a matter of some debate among Republicans.

While Bannon has argued that winning money for the wall is critical for Republicans to have any chance of holding onto the House – “The wall is not just totemic. The wall is absolutely central to his program,” he told CNN in June – others think that not even his hardcore base ever truly believed Trump would actually build one.

Rick Tyler, who worked for Texas Sen. Ted Cruz’s 2016 presidential campaign, said Trump’s promise to build a wall and make Mexico pay for it was simply something he invented for his rally speeches. “The whole wall thing was a shtick,” he said, likening Trump’s rallies to professional wrestling shows where the audience is in on all of the set pieces. “As long as they were applauding it, he was going to go keep repeating it. It’s just part of the concert lineup.”

GOP consultant Frank Luntz said he doubts most of Trump’s strongest supporters will even learn that he failed to get wall money in the pending spending bill. The fight over Trump’s Supreme Court nominee, Brett Kavanaugh, “what’s happening in China and a host of other issues will overshadow this,” he said.

Wilson, who recently published a book excoriating Trump, said the president’s most loyal supporters ignore news sources that do not portray him in a flattering light. “His base would literally believe that a bucket of dung was a bucket of ice cream if he told them it was,” he said. “He’s going to do his rallies and claim the wall is already halfway built, and it’s 400 feet tall. And people will cheer and whoop.”

Krikorian, nevertheless, does not believe that Trump can get away forever with promising a wall but never delivering. “The president has talked himself into a box,” he said. “You can’t keep making threats and not follow up.”

This story has been updated with comment from the White House.