(Zoeann Murphy/The Washington Post)

Rush Limbaugh and listeners of his conservative radio show were not happy with reports this week that President Trump was, as Limbaugh put it, “caving on his demand for a measly $1 billion in the budget for his wall on the border with Mexico.”

Tim from Detroit called in to say he’s worried Trump will “kick this can down the road” like any other politician. Ray from Chattanooga, Tenn., wished he could tell Trump: “Be the man we elected you to be.”

And John from Polk City, Fla., added: “Number one, build the wall. Every time he spoke: Build a wall. I’m afraid he’s starting to dip his foot into the swamp. And, boy, I just don’t want to see that happen.”

In his bumpy first three months in office, Trump has reversed himself on campaign promises now seen as impractical or unnecessary, from repealing and replacing Obamacare in a single day to labeling China as a currency manipulator.

But Trump’s promise to build an “impenetrable, physical, tall, powerful, beautiful southern border wall” paid for by Mexico was special. It was his most vivid campaign promise, and its proposed height grew with every obstacle thrown in Trump’s way, from naysayers saying it wasn’t possible to the Mexican government saying it wouldn’t foot the bill. The most popular chant at campaign rallies became “Build that wall!”

(The Washington Post)

Failing to quickly follow through on a wall carries real political risks for Trump, whose success is due in large part to his embrace of hard-line positions on immigration. There is also peril for fellow Republicans — who have been split for years on how the United States should reform its immigration system — in not taking the idea of the wall seriously enough.

Mark Krikorian, the longtime executive director of the Center for Immigration Studies, a think tank that advocates reduced immigration, said that he has never considered a border wall a top priority.

But now that the wall has taken on a life of its own, Krikorian said that Trump and Republicans have to make some sort of progress in securing a chunk of the border with a wall or heavy-duty fence — or else blow the opportunity to show Americans the party is ready to take action to crack down on illegal immigration.

“Following through on wall construction is one of the ways that the political class can win back trust on this topic,” Krikorian said. “It’s a tangible thing. You can take pictures of it and imagine it in your head.”

He added: “Even if the border wall did no good at all to control immigration, it would be important to build . . . Even if it did nothing, even if it was completely ineffective, it’s important politically.”

To Trump, the wall is a concrete symbol of his commitment to cracking down on illegal immigration. To many lawmakers, it’s a fantastical joke that they have to carefully navigate.

Why Trump’s wall contradicts today’s immigration trends.

Since Trump took office, many lawmakers have been trying to steer him toward more practical solutions for the border involving fencing, increased border patrols and technology. They argue that constructing a wall would cost tens of billions, still wouldn’t solve many of the country’s border problems and could create whole new challenges as well.

“I think we’re all recognizing that his message is one that he wants a secure border. I think at one point that he may have very well thought that that was the best way to do it,” said Sen. Mike Rounds (R-S.D.).

Even at the White House, aides have been shifting their messaging to the broad topic of “border security,” with White House Chief of Staff Reince Priebus using the phrase six times on NBC’s “Meet the Press” on Sunday while only saying the word “wall” twice. The next day, Trump softened his demand to include wall funding in a must-pass spending bill — a comment widely viewed as caving to pressure from the same lawmakers that Trump once bragged he could outsmart.

Trump began talking about a southern border structure even before he launched his campaign, bragging that he was “the king of building walls.” In his announcement speech in June 2015, Trump promised: “I will build a great wall on our southern border, and I will have Mexico pay for that wall. Mark my words.”

He continued that messaging this week, telling the Associated Press that “the wall’s getting built, okay?” White House press secretary Sean Spicer reiterated the point during a Tuesday briefing — “There will be a wall built,” he said — but dodged questions about when and how.

But with an estimated price tag as high as $21.6 billion, lawmakers have been slow to lend their support. On the wall and a host of other issues, they often emphasize Trump’s lack of experience in politics in explaining why he is altering his positions.

“Some of the things that were said during the campaign, I think he now knows simply aren’t the way things ought to be,” Senate Majority Leader Mitch McConnell (R-Ky.) told Newsmax TV earlier this month following Trump’s change of heart on whether NATO was obsolete. “He’s learning the job.”

While Trump has long been clear about wanting a physical wall on the border, other Republicans have put their own spins on one of his most controversial campaign promises.

“What I hope he means is that we should be talking about establishing operational control . . . I’m not saying necessarily walls,” said Rep. Charlie Dent (R-Pa.), a centrist who at times has been openly critical of Trump.

Meanwhile, Rep. Chris Collins (R-N.Y.), a Trump ally, took the president at his word: “It’s a physical wall. There’s no ifs, ands or buts about that.”

Others have been left guessing.

“I’m not an interpreter — you’ve got to ask them what they mean. I mean, that’s their initiative, obviously. I take it he’s taking about border security in general,” said Sen. Marco Rubio (R-Fla.).

For Trump, and for many of the voters who helped propel him to victory, there should be no misunderstanding.

“The wall’s going to get built, folks. In case anybody has any questions, the wall is going to get built,” Trump told reporters during the signing of an executive order related to agriculture Tuesday. “I watch these shows, and the pundits in the morning, they don’t know what they’re talking about. The wall gets built, 100 percent.”