For all his hardline immigration promises, Donald Trump has apparently run up against a wall.

The wall.

In a recent round of muddled Twitter messages, seemingly to reassure his base he hasn't gone soft on immigration, the U.S. president took a tough line.

He pronounced the end of a deal to protect young immigrants shielded from deportation by the Deferred Action for Childhood Arrivals program, declaring, "DACA is dead."

He later introduced policies to make it harder for people to claim asylum. And on Wednesday, he signed a proclamation to immediately deploy the National Guard to the southern border.

A Mexican child peers through the border fence near El Paso, Texas. President George W. Bush erected more than 1,100 kilometres of fencing along the border in 2007 to beef up border security. (Jason Burles/CBC)

No matter what he throws out there, though, no anti-immigrant provision sticks for some of Trump's base like his signature campaign promise: Construction of "a big, beautiful" concrete wall. The problem? The time to secure funding for the physical barrier has likely passed.

"It's more or less a dead issue" until after the November midterm elections, says Josh Huder, a senior fellow with Georgetown University's Government Affairs Institute.

What killed it, he says, was Trump's signing of last month's omnibus spending bill, which amounted to a death warrant for the $25-billion project to cover part of the nearly 3,200-kilometre border with Mexico.

"It was his last, best chance to secure wall funding this year," Huder said.

U.S. President Donald Trump listens during a news conference in the White House during the United States-Baltic Summit on Tuesday. On Wednesday he signed a proclamation to immediately deploy the National Guard to the country's southern border. (Alex Wong/Getty Images)

Trump's base was reportedly aghast.

"I am so upset and disappointed in President Trump for not vetoing that horrible spending bill," Gene Moretti, a Trump supporter and real-estate photographer in New Jersey, fumed over Twitter. How, Moretti asked, could Trump "let" Republican lawmakers "get away with not funding your biggest promise of building the wall?"

(In an email to CBC News, Moretti clarified he still supports Trump "100 per cent," despite being dismayed.)

A section of the U.S.-Mexico border in Arizona. (Jason Burles/CBC)

"The $1.3 trillion spending bill allocates ZERO for the wall. Biggest mistake Trump made was to sign it," conservative radio host Jeff Kuhner tweeted. "He betrayed his base."

The new plan signed on Wednesday to militarize the border sounds like compensation for the letdown of "losing on the wall," said Kevin Appleby, senior director of international migration policy at the Center for Migration Studies.

"I think it's to save face," Appleby said. "He's basically throwing a little temper tantrum because he's been criticized on the right and the left about not fulfilling his campaign promise."

It didn't have to be this way. Democrats offered to cut a wall-for-DACA deal that would have extended protections for nearly 700,000 young undocumented Dreamers in exchange for wall funding.

White House adviser Stephen Miller arrives aboard Air Force One, returning to Washington with Trump from a weekend in Florida, on March 5, 2017. Miller is considered the chief ideological anti-immigration influence in the Oval Office. (Jonathan Ernst/Reuters)

But negotiations broke down, reportedly after Trump senior adviser Stephen Miller, considered the chief ideological anti-immigration influence in the Oval Office, became involved. The conservative confidant also wanted to reduce legal immigration, and was seen as appealing too much to hardline groups that rejected amnesty for 1.8 million Dreamers seeking citizenship. Miller spent the Easter weekend with Trump at Mar-a-Lago and reportedly warned him about immigration policies losing support from more nativist elements in his base.

"You could make the case that Miller killed the wall," Appleby said. "The thing is, I don't know if Trump realizes that."

Instead, last month's spending bill allocated only $1.6 billion for a barrier on the southern border to upgrade existing fencing. Trump called it a wall "down payment."

In many places, the border fence near Los Indios, Texas, cuts into farmland, forcing farmers to cross gaps in it to tend their property. (Jason Burles/CBC)

That's not exactly what conservative firebrand and ex-Trump evangelist Ann Coulter, who slammed the president last week as a "lazy ignoramus," had in mind.

"He's not giving us what he promised at every single campaign stop," Coulter told an audience last week at Columbia University.

A mural painted on a wall at the border in Arizona. (Jason Burles/CBC)

Which brings us to the administration's order to send the National Guard to the border. The strategy has no price tag, but falls short of the original desire for a 3,200-kilometre concrete wall, or even the more modest 1,160-kilometre fence-and-wall barrier.

Alabama Republican consultant John Gray acknowledged Trump likely "knew he couldn't get the wall." But he argues anyone who takes "the wall" to mean a physical barrier — rather than a network of security measures that could include E-Verify, vehicle barriers, snipers, drones, "bear traps and a river loaded with alligators" — is missing the subtext.

The wall is shorthand, Gray believes, "for fixing the problem of illegal immigration." That Trump still secured more funding in the most recent spending bill for the military, which is now being deployed to the border, speaks to his point.

"Voters don't give a shit about the wall," he said. "There isn't a single voter out there that dreams about a 40-foot wall made of poured concrete."

A U.S. Customs and Border Protection truck is parked near the border in Arizona. (Jason Burles/CBC)

Coulter would beg to differ. In an interview Tuesday with conservative radio, she said the wall stands as a "metaphor" for cracking down on illegal immigration.

"But it also means building a physical wall. And I don't think we're getting it."

Matt Glassman, who teaches a class on Congress at Georgetown University, said it remains a long shot that an "actual, massive physical wall, like a Great Wall of China," as promised during Trump's 2016 presidential campaign, will ever materialize.

Trump's last major vehicle on the congressional agenda would be a continuing resolution in September. It's possible to attach border-wall funding to that, but it's unlikely, given that the Democrats won't want to compromise so near to November's midterm elections, Glassman said.

A member of U.S. Customs and Border Protection sits in his truck near the border in Arizona. (Jason Burles/CBC)

Three options to build a wall are still available, though they're "heavy lifts," according to Rachel Bovard, senior director of policy for The Conservative Partnership, a nonprofit aimed at promoting limited government:

A law codified by the Department of Homeland Security allows for construction of reinforced fencing along at least 1,100 kilometres of the border, but the department lacks the funding to take on such a huge project, Bovard said.



The "military option" would have Congress appropriate a chunk of the $700-billion allocated to the Department of Defence for wall-building, though this would be unlikely to be authorized by lawmakers.



The president might use a provision in a renegotiated North American Free Trade Agreement that might allow for wall funding if he can make a legal case it's necessary for trade with Mexico.

A portion of the border fence stands in Nogales, Ariz. Trump says he's willing to shut down the government in order to secure funding in the next budget for his proposed border wall. (Jason Burles/CBC)

Again, Bovard said, it wouldn't be so easy.

"Congress really went out of their way to block Trump from doing this," she said, noting that the $1.6 billion also blocks him from using the funds on wall prototypes — "a stab in the eye from the president's own party."

"In the end, it all comes back to Congress," she said. "Congress deserves a lot of blame for putting him in this position."