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(CNN) -- Fights over money to pay for a border wall -- as well as Obamacare subsidies and an infusion of resources for the military -- are threatening to trip up congressional talks over a funding bill to head off a government shutdown Friday.

Bipartisan negotiators have spent weeks methodically working through hundreds of issues to set spending across all federal agencies for the rest of the fiscal year, with White House officials largely on the sidelines being briefed on various issues.

But Democrats are warning that the White House, which stayed out of the fray during much of these talks, is ratcheting up demands, insisting on including border wall money in exchange for continuing to pay insurance companies subsidies to bolster the Obamacare marketplace, which they say is a nonstarter. President Donald Trump highlighted the issue over the weekend and on Monday.

"The Wall is a very important tool in stopping drugs from pouring into our country and poisoning our youth (and many others)!" Trump tweeted.

But White House officials said late Sunday that they did not want the government to shut down over any impasse in the spending talks -- and that's a directive straight from the President.

Top administration officials explained to the President this weekend that the most likely scenario is a stopgap bill that would last a week or so until a deal is reached. "There's no interest in a shutdown," an official says, adding they will "do what it takes" to avoid one.

Aides for the top Republicans and Democrats on the appropriations committees say they are making progress under the deadline pressure. But they also concede that significant sticking points remain and Congress, which is returning from a two-week recess, will have just a few days to get a bill to the President's desk.

Multiple aides tell CNN that Congress may need to pass a stopgap measure -- potentially for a week or more -- to give them time to reach a final deal.

Details of a final deal are scarce. House Republicans said their leadership was short on specifics during a private conference call Saturday with Republican members in part because of fear that the call could be leaked.

"I don't think the budget's fully baked yet. ... But that will consume us next week," one Republican member told CNN after the call.

Congressional Republicans recognize that conservatives are unlikely to back any measure so they are working across the aisle to get support on a bill that will pass with votes from both parties.

Trump has few legislative accomplishments to show for his first 100 days in office -- a mark that he will hit on the same day as the deadline to fund the government. Sources close to the process tell CNN that dynamic has increased pressure on the new administration to show some results on one or more of their campaign promises, especially after legislation to repeal and replace Obamacare failed to gain enough support to even get a vote last month.

There's a renewed effort to bring back GOP Obamacare bill and try to hold a vote as early as next week in the House. Talks over the recess have resulted in an agreement among some conservatives and moderates on some potential tweaks. But many members and aides caution that with the clock ticking down getting a final health care deal that can pass and a spending bill over the finish line is a heavy lift.

"I think it's highly unlikely we can do both next week, so I think funding the government should have the priority," Rep. Bradley Byrne of Alabama told CNN in a phone interview Friday.

Even if Congress doesn't include money for the wall in this week's measure, the administration appears to be looking for other ways to pay for the project. Attorney General Jeff Sessions said Sunday there are a number of ways to extract the billions of dollars needed to build Trump's wall.

"We're going to get it paid for one way or the other," Sessions told ABC's "This Week," referencing a Treasury Department watchdog report during the Obama administration that said excess payments of about $4 billion a year were going to people that shouldn't get them, and he said reining in the problem could lead to savings over time that could pay for the wall.

Trump's Budget Director Mick Mulvaney acknowledged Friday to reporters that there are still a number of disagreements between the administration and GOP leaders as well as Democratic lawmakers on Capitol Hill that are holding up a deal, including money to begin construction of a border wall.

The OMB Director told the Associated Press on Thursday "we want wall funding. We want (immigration) agents. Those are our priorities." He essentially dismissed Democratic opposition to the wall, arguing Trump's election in November meant he should get a top agenda item through Congress.

Democrats have repeatedly said they oppose the border wall, and including money in this must-pass bill was a red line they wouldn't cross.

House Minority Leader Nancy Pelosi, in a conference call Thursday night with House Democrats, began to lay the groundwork for blaming the GOP, arguing with control of the majority "it's their responsibility" to keep government open.

"We have the leverage and they have the exposure," Pelosi said, reminding members that without their help Republicans would walk right into a shutdown.

While many Republicans agree there should be more resources to beef up border security, there isn't the same drive among most rank and file members to risk a shutdown over what amounts to a down payment to begin building a border wall.

"I would say I don't see an appetite to have a government shutdown," Illinois GOP Rep. Rodney Davis said on CNN on Friday. He warned, "I was part of Congress during the last government shut down. It was very frustrating to somebody like me who went to Washington to govern."

On Friday White House press secretary Sean Spicer reiterated the administration was continuing to push for these items that Democrats oppose.

"I think we've made it very clear that we want border wall funding and we want greater latitude to deny federal grants to sanctuary cities, we want hiring of immigration agents and we want $30 billion to infuse the military budget. Those are our priorities," Spicer said.

Mulvaney floated a proposal Friday that would offer Democrats one dollar in Obamacare spending for each dollar in the bill to pay for building a wall along the southwest border.

But Matt House, spokesman for Senate Democratic Leader Chuck Schumer, blasted that proposal, saying, "the White House gambit to hold hostage health care for millions of Americans, in order to force American taxpayers to foot the bill for a wall that the President said would be paid for by Mexico is a complete non-starter."

House added that "the US government is supposed to take care of its citizens and, according to the President, Mexico is supposed to pay for the wall. If the administration would drop their eleventh hour demand for a wall that Democrats, and a good number of Republicans oppose, Congressional leaders could quickly reach a deal."

Democrats are also pressing the Administration not just to continue paying out the subsidies to insurance companies providing coverage in the Obamacare exchanges, but to agree to put a mechanism in place to allow the Department of Health and Human Services to provide these subsidies to insurers going forward.

Another thorny issue is the amount negotiators set for the Pentagon. Defense hawks in Congress have argued that the military is stretched too thin right now and argue the billions they're pushing for is emergency money that needs to be dedicated to promote readiness and purchase weapons systems and boost operations in hot spots around the globe.

Byrne, a member of the House Armed Services Committee, said he doesn't want a shutdown, but that he and others who are pushing for the increase for the military made it clear to top Republican leaders "we're not just going to roll over on that."

Byrne said he's normally willing to help pass spending bills when other conservatives balk, but may not be there this time if the final package doesn't include sufficient resources for troops. "I don't see the leadership having the votes to move a long-term CR or any sort of appropriations bill without those of us who have big concerns with defense," he said referring to a continuing resolution, one type of spending bill Congress could pass to keep the government funded.

CNN's Jeff Zeleny, MJ Lee, Lauren Fox and Jim Acosta contributed to this report.