WASHINGTON — White House press secretary Sarah Sanders said on Tuesday that President Donald Trump might be willing to accept less than $5 billion for his promised border wall in a year-end spending bill, provided that other funds could be used to close the gap.

"At the end of the day we don't want to shut down the government," Sanders told Fox News' Bill Hemmer. "We want to shut down the border."

Her remarks represent a new tack from the White House since Trump proclaimed in an Oval Office meeting with top congressional Democratic leaders last week that he would be "proud" to shut down part of the government in service of forcing Congress to give him the full $5 billion he wants for the border wall.

Sen. Brian Schatz, D-Hawaii, who serves on the Appropriations Committee, said Trump had painted himself into a political corner and is now scrambling to get free.

"They are realizing that they don’t have any leverage here," Schatz said in a telephone interview with NBC News. "They're looking for a face-saving way out."

Later, during a rare White House press briefing, Sanders said Trump is waiting for Congress to act.

"We want to see what the Senate can pass," she said.

Trump also weighed in, saying, "We'll see what happens."

"It's too early the tell — we need border security," Trump told reporters Tuesday afternoon during in a school safety event at the White House.

On Capitol Hill, Republican and Democratic senators said they were discussing ways to fund the federal agencies that will run out of spending authority if a deal isn't reached by Friday.

Senate Majority Leader Mitch McConnell, R-Ky., huddled with Minority Leader Chuck Schumer, D-N.Y., and the top members of the Appropriations Committee, Alabama Republican Richard Shelby and Vermont Democrat Patrick Leahy, in his office Tuesday morning.

"We’re talking and it was very broad. We’re waiting to see details," Schumer said, adding that he hasn't "heard a peep" from the White House.

A Senate Democratic aide later told NBC News that Schumer called McConnell to reject a GOP proposal to add $1 billion in fungible funds to implement Trump's immigration agenda to the $1.6 billion for wall funding that was expected to be included in a spending measure for the Department of Homeland Security's operations.

While the White House put the onus on the Senate, McConnell said he needs more guidance from the president.

"I'm in consultation with the White House about the way forward," he said. "We'll have more to say about that hopefully a little bit later — about what the president is willing to sign."

Republicans control both chambers of Congress until January, when Democrats will take power in the House. But, because of the filibuster power in the Senate, they'll need to peel off a significant portion of the Democratic caucus to win support for a deal.

House Minority Leader Nancy Pelosi, D-Calif., told reporters Tuesday that the wall is a non-starter for her.

"Understand this," she said, "the wall is not about money. "The wall is about morality. It's the wrong thing to do. It doesn't work."

The heads of some federal departments, including the Pentagon and the Homeland Security Department, have certain authorities to transfer appropriated funds between programs, and it's possible Congress could grant even greater transfer authority with an eye toward honoring Trump's wish for more border-wall funding in a year-end spending agreement.

Sanders said Trump is exploring his options for funneling money from other agencies to border-protection accounts.

"The president's asked every agency to look and see if they have money that can be used for that purpose," she said.

Lawmakers said they don't know what the president wants to do in terms of reprogramming money.

"He does have the power to defend the country, has the power to protect the borders, I think that would be inherent in the Constitution, but as for the specifics I haven’t seen any specifics," Shelby said. "And what we’re working on now is how to get all of the stuff funded and the clocks ticking, what midnight Friday."

Pelosi, who spoke to reporters on her way to Schumer's office, said Congress should have a role if the president wants to move money around.

"You have to reprogram by coming to Congress — unless he has another plan," she said. "We'll see."

Defense Secretary Jim Mattis has the authority to transfer up to $4 billion dollars between Pentagon programs each year. But the transfers must meet a series of criteria — including that a request for funding has not been denied by Congress — and he must notify lawmakers of any movement of money.

In the past, notification has meant sign-off from top committee Republicans and Democrats in Congress, but that could become a point of contention between the White House and congressional Democrats.

"I would never use Nancy Pelosi as my source for legal authority on anything," Sanders said.