President Donald Trump and White House officials pressed congressional Republicans on Sunday to use the looming threat of a government shutdown to win funding for a wall along the U.S.-Mexico border, a top priority for the administration as it nears the symbolic 100-day mark.

Trump wants funding to be included in a spending measure that would keep the government open past Friday, a determined effort that has prompted a possible standoff with lawmakers in both parties, who hope to avert a federal shutdown next weekend.

Trumpโ€™s push for fast action on his pledge to build the border wall is part of a mounting and, at times, tense scramble inside the administration to kick-start the presidentโ€™s agenda, even if it risks dire political consequences. It follows weeks of frustration within the White House over inaction and stalemates on Capitol Hill over big-ticket items such as health care and tax cuts.

White House Chief of Staff Reince Priebus said in an interview on Sunday with The Washington Post that the president and his advisers remain โ€œstrongโ€ in their commitment to securing funding for border security and a wall.

โ€œThis is what the president ran on,โ€ Priebus said. โ€œWe want to get to a place this week where border-security money is being directed to the Department of Homeland Security so that we can begin surveillance and preliminary work, and then we will keep working on getting DHS what it needs for the structure.โ€

The timing promises a week of high drama on the Hill. The Senate returns on tonight, and the House returns on Tuesday from a two-week recess, leaving just three days when both chambers will be in session to wrangle out a funding agreement. Negotiators worked throughout the break, but thus far a deal has not been struck.

The wall, which experts say would cost $21.6 billion and take 3ยฝ years to construct, has emerged as a crucial sticking point for the White House, with the president insisting privately and publicly that progress toward its funding and eventual construction must be showcased this week.

โ€œCongress is right to be nervous, but thatโ€™s Trumpโ€™s style to be aggressive, ambitious, right out of The Art of the Deal, โ€ said William Bennett, a conservative commentator and close friend of House Speaker Paul Ryan, R-Wis. โ€œEveryone seems to be getting used to that and how Trump doesnโ€™t want the half loaf but the whole loaf.โ€

In a tweet on Sunday, Trump elbowed Democrats who have resisted his call to include wall funding. He chastised them for not wanting โ€œmoney from the budget going to the border wall despite the fact that it will stop drugsโ€ and gang activity, in his view.

Trump added that he would continue to ask Mexico to pay for the project, another bold proclamation he made during the campaign. Meanwhile, he said, he will press Congress for funding โ€œso we can get started earlyโ€ on the โ€œbadly needed border wall.โ€

It remained unclear on Sunday whether moderates within the GOP could convince the White House to avoid a shutdown. Democrats have insisted that they will not vote for any spending bill that gives the White House money or flexibility to begin construction of a border barrier. They believe that the GOP will have to either abandon Trumpโ€™s demand or assume political responsibility if a shutdown occurs.

โ€œThe burden to keep it open is on the Republicans,โ€ House Minority Leader Nancy Pelosi, D-Calif., said Sunday on NBCโ€™s Meet the Press. โ€œBuilding a wall is not an answer. Not here or any place.โ€

Inside the White House on Sunday, West Wing aides made calls to congressional allies, while the president tweeted and reached out to several advisers, according to three officials who spoke on the condition of anonymity because they were not authorized to speak publicly.

Trumpโ€™s tweets included a shot at Democrats in which he drew parallels between border-wall funding and continued federal payments for subsidies under the Affordable Care Act. Some Trump associates said that they believe Democrats may be willing to deal on border funding if those payments are put on the table this week during cross-party talks.

โ€œObamaCare is in serious trouble. The Dems need big money to keep it going โ€” otherwise it dies far sooner than anyone would have thought,โ€ Trump tweeted. He later followed: โ€œThe Democrats donโ€™t want money from budget going to border wall despite the fact that it will stop drugs and very bad MS-13 gang members.โ€

The tweets did little to assuage concerns created earlier in the day when White House budget director Mick Mulvaney suggested that Trump might not sign a spending bill that does not meet his demands.

โ€œWill he sign a government funding bill that does not include funding for the border wall?โ€ Chris Wallace, host of Fox News Sunday, asked Mulvaney during a televised interview.

โ€œWe donโ€™t know yet,โ€ Mulvaney replied.

Mulvaney said that the White House expects Democrats to cave on the border wall in exchange for guaranteed payments under the ACA.

But Pelosi and Senate Minority Leader Charles Schumer, D-N.Y., already have rejected a White House offer to build into the spending bill a dollar-for-dollar match in wall funding and federal health-care payments. Negotiators want the stopgap measure to keep government open by keeping spending flat, including money to keep the ACA going. Trump is hoping to open that up for negotiation in exchange for wall money.

Democrats believe that voters will blame Trump for a shutdown, particularly if congressional leaders omit wall funding from a spending deal. Democrats and GOP leaders appeared to be nearing a spending agreement last week before Trump ramped up his demands.

Aides hailed the budget talks as one of the only active discussions in which Democrats and Republicans maintained common ground. One clear area of agreement was not to include border funding in the stopgap budget. Democrats agreed to include other border-security measures, including money for new drones to patrol the border, but it was agreed that the wall itself should be debated separately, after the government is kept open.

Sen. Marco Rubio, R-Fla., is among a group of prominent Senate Republicans who have said publicly that they hope to avoid a border wall fight this week.

โ€œI think thatโ€™s a fight worth having and a conversation and a debate worth having for 2018,โ€ Rubio said Sunday on CBSโ€™ Face the Nation. โ€œIf we can do some of that now, that would be great. But we cannot shut down the government right now.

Mulvaneyโ€™s hard-line stance also is odds with a White House faction convinced that a government shutdown would be cataclysmic for an administration already struggling to prove its ability to govern, according to GOP aides in the White House and Congress who spoke on the condition of anonymity to discuss the ongoing talks.

Republican leaders have signaled that they will concentrate this week on keeping the government open, even if that means ignoring White House calls for action on other major priorities, such as rewriting the tax code and overhauling the ACA.

Trump has pushed his staff in recent days to prod House Republicans for final revisions in a health-care proposal that can win support from both the hard-line conservative Freedom Caucus and the moderate Tuesday Group. And that task led advisers over the weekend to rely especially on three key players โ€” Rep. Tom MacArthur, R-N.J., co-chairman of the Tuesday Group; Rep. Mark Meadows R-N.C., chairman of the Freedom Caucus; and Rep. Patrick McHenry, R-N.C., the House GOP chief deputy whip โ€” to finalize legislation.

But the White Houseโ€™s efforts to work directly with various House coalitions and piece together a compromise health care package has led to private unease on Capitol Hill, where some GOP members close to the leadership have grumbled that Trump aides are setting up the party for defeat or a stumble should the tweaked health bill not have as strong support as the White House has suggested.

Trumpโ€™s advisers, aware of those concerns, still plowed forward Sunday on crafting the billโ€™s language, citing the presidentโ€™s desire for action. There were ongoing conversations about the timing for a health vote, with Wednesday, Thursday, Friday or even sometime in early May, if necessary, discussed as options.

Ryan addressed that pressure in a conference call Saturday afternoon, in which he told GOP members that while he hoped that they would continue health care talks, his top priority will be the stopgap spending bill.

โ€œWherever we land will be a product the president can and will support.โ€ Ryan said, according to a senior GOP aide on the call.