President Trump and congressional Republicans ramped up promises this week for a battle over the president’s U.S.-Mexico border wall after the midterm elections. But there’s no plan for getting Trump the wall money he wants — raising the possibility of a government shutdown fight just before Christmas.

House Speaker Paul D. Ryan (R-Wis.) and Senate Majority Leader Mitch McConnell (R-Ky.) both pledged this week to push for Trump’s wall money. Trump himself doubled down on the issue Thursday, saying in an interview on “Fox & Friends”: “Right after the election we’re doing something very strong on the wall.”

But after spending months persuading Trump to put off his border wall fight until after the election, GOP leaders now face the possibility of emerging empty-handed from the fight they postponed. They don’t have enough votes in the Senate to push through a big wall-funding increase, and the midterm elections could weaken their position even further.

That leaves a partial government shutdown as a real possibility, because no one on Capitol Hill or at the White House has come up with a viable strategy to increase border wall funding to the levels Trump wants.

Asked this week if there was a plan to get Trump his wall money, Senate Appropriations Chairman Richard C. Shelby (R-Ala.) replied: “Not that I know of. And I think I’d know.”

Such a shutdown would be limited to the Department of Homeland Security and a handful of other agencies because most of the government — including the Pentagon — has already been funded through next September. But funding for Homeland Security, which pays for the border wall, runs out Dec. 8, so Congress must act before then to keep the agency running.

Trump himself has continued to raise the threat of a shutdown to try to force funding for the wall, as his frustration on the issue has only grown. At times it’s directed at his own budget director, Mick Mulvaney, for not asking Congress for more wall money to begin with. Trump repeatedly promised during the campaign that the wall would be paid for by Mexico.

More recently Mulvaney has been looking for vehicles for wall funding at the president’s direction. Trump is asking for at least $5 billion, and Mulvaney was upset when Congress approved a bill last week reauthorizing the Federal Aviation Administration that included money for disaster relief but not for the wall, according to two White House officials who spoke on the condition of anonymity to disclose confidential deliberations.

Shelby and others anticipate the White House could send up an emergency spending request to deal with the most recent hurricanes, and that could become another vehicle to add wall money by year’s end.

The outcome of the midterm elections is certain to be an important factor, with potential to increase Democratic resolve to defy Trump, or embolden Republicans to fight for his agenda. And if Republicans lose the House, they could see the post-election lame-duck session as their last opportunity to push through immigration bills Trump wants before their majority evaporates with a new Congress in January — even if those bills face certain death in the Senate.

A major battle over wall funding already threatens to consume the lame-duck session. House Majority Leader Kevin McCarthy (R-Calif.), who is jockeying to become speaker if Republicans keep the majority, plans to introduce a hard-line immigration bill as early as Friday that would appropriate $23.4 billion to fully pay for the wall. He wants to bring it to a vote after the election, a move that could help win conservative support for his leadership ambitions.

The price tag on McCarthy’s wall bill is far higher than Trump’s current ask of $5 billion for 2019, and far, far higher than the $1.6 billion agreed to in the Senate on a bipartisan basis.

From $1.6 billion to nearly $25 billion is “a quantum leap,” Shelby remarked Thursday.

Some in the White House support McCarthy’s bill, but they view its prospects as “uphill at best,” according to a senior administration official who demanded anonymity to speak freely.

Trump on Thursday blamed Democrats for blocking the wall.

“They don’t want to give us the wall, they fight in unison because they think that’s a good political thing,” Trump said on “Fox & Friends.” “The truth is that’s good for our country. We need the wall.”

If Trump’s insistence results in a partial government shutdown, it might be because there are few other options for Republicans to try to secure wall funding. But Democrats are already dismissing the notion that shutting down the Department of Homeland Security would give Trump the result he wants on the wall.

“Having been to the table two or three times with the wall and immigration, I have no confidence this administration can reach an agreement,” said Sen. Richard J. Durbin (D-Ill.).

“I don’t think a shutdown is anything the Republicans can brag about since they’re in charge,” Durbin added. “I think it would be a further illustration of the ineptitude of this party when it’s in control.”

Republican leaders spent months coaxing Trump to put off a fight over the wall until after the midterms, convinced that a pre-election shutdown would be terrible politics. But it’s never been clear why they would be in any better position to achieve wall funding after the election than they are now.

Ryan said this week that there would be a “big fight” on the issue after the election, though he said the outcome was unknown. McConnell told the Associated Press that “we’re committed to helping the president try to get the wall funding” in the lame-duck session.

McConnell also downplayed the implications of a shutdown, saying, “That episode, if it occurs would be in that portion of the government that we haven’t funded. Seventy-five percent of it we did fund before the end of the fiscal year.”

There’s also some discussion on Capitol Hill of trying to revive a larger deal that would give Trump a big chunk of wall money in exchange for protections for immigrants brought to the country illegally as children under the Deferred Action for Childhood Arrivals program. But attempts to strike such deals have collapsed several times during Trump’s presidency and optimism appears limited, even among supporters of comprehensive immigration legislation.

“All I can say is, we’ll see,” said Sen. Lindsey O. Graham (R-S.C.). “Wall funding for DACA is a good deal, but we’ll see if it works.”

Gabriel Pogrund contributed to this report.