Amid Democratic opposition, Republican leaders are retreating from President Donald Trump’s very popular campaign promise to build a border fence to block illegal immigration, drug smugglers, and criminals.

A top GOP leader, Sen. Roy Blunt, told reporters on Tuesday that GOP leaders do not want to include Trump’s spending for the border wall in the spring budget, which is due by April 28. “All of the committees, the leaderships of the House and Senate, are working together to try to finalize the rest of the FY17 [budget spending] bill,” he added. “My guess is that comes together better without the [border] supplemental,” he told The Hill. But GOP leaders may include some border spending in a separate 2017 budget for the military, Blunt suggested.

The tacit retreat comes only a few days after GOP leaders staged and lost a fight to push their own business-friendly version of an Obamacare reform, and amid GOP calls for Trump to help pass their hoped-for tax cut.

Top Democrats are hoping to wreck Trump’s presidency by blocking any funding for his key campaign promise. “The wall is a poison-pill rider,” Schumer said in an interview with Politico. “They’ll do it at their peril.”

On March 16, Trump has asked Congress for $1 billion to jump-start border security and to help build the first 62 miles of border barrier in 2017. The overall request was included in the March supplemental request asking for $28 billion for various near-term projects, including $25 billion for the military.

The Democrats’ high-profile opposition to the wall creates a bargaining chip that the establishment GOP can trade to help win its primary goals, such as tax cuts that aid donors and companies.

But the GOP can win any political fight caused by Democratic opposition to the wall, a source told Politico:

A senior Republican source suggested Trump could conceivably win a shutdown fight if he went to the mat to defend it: “This is his signature issue. I cannot imagine a scenario where the Trump administration loses on the border wall funding. If I were them, I’d dare the Democrats to shut down the government over this.”

Numerous polls show that strong majorities of Americans want to reduce the flow of drugs, preserve U.S. jobs for Americans and also want Congress to pass laws that help Americans. In 2006, Congress passed a law authorizing — but not funding — the construction of a border wall.

Politico also reported that another senior GOP senate leader, Sen. John Cornyn, was trying to avoid a Democratic filibuster of the April 28, 2017 budget update by dumping Trump’s request for wall spending.

While no decision has been made by GOP leadership, Republican lawmakers may decide to decouple the two [the wall spending and the April 28 budget supplement] to avoid a confrontation with Democrats. If they do, the chances of getting Trump’s wall funding passed this spring become slim. “It remains to be seen,” said Senate Majority Whip John Cornyn (R-Texas) in an interview. “What I would like to see is a plan for how the money would be spent and a good faith discussion about what border security is really composed of. We haven’t had that.” Asked about the prospects for a lapse in government funding, Cornyn was definitive: “There’s not going to be a shutdown.”

Some GOP senators are openly looking for ways to stop Trump’s wall, which is intended to reduce the inflow of cheap labor to employers in their states, along with reducing the inflow of drugs and criminals.

“The border wall is probably not a smart investment,” said South Carolina Sen. Lindsey Graham told Politico. In 2012, Graham launched the “Gang of Eight” amnesty bill which split the GOP and helped elect Trump as president.

North Carolina Sen. Tom Tillis is downplaying the wall as he calls for a greater inflow of cheap labor. On March 2, he joined with several lobbyists to suggest that Congress deny funds for construction of a wall or fence along stretches of the border in favor of “other capabilities.” Border security, Tillis said, “is one of the first things we need to do… [but] it seems to me we could get to a reasonable compromise on a bill that I think will be less costly and more effective than just the concept of a structure. Walls need to be where wall are, but other capabilities need to be elsewhere.”

Tillis and Graham both want to hold funding for a wall hostage to approval for new laws allowing more foreign lower-wage contract workers to get jobs sought by Americans at normal wages.

In December, a top ally of House Speaker Paul Ryan outlined the GOP leadership’s strategy to isolate and block Trump’s populist campaign promises, likely including his popular immigration reforms. “Let’s do the things where we agree — let’s do tax reform, let’s do Obamacare, let’s replace Obamacare, let’s start dealing with border security, let’s rebuild our national security and then, on those areas where his agenda is not exactly aligned with ours … then, we’ll figure out the rest in the next six months,” Flores told Arthur Brooks, president of the American Enterprise Institute.