The Trump White House maintained its hard line on funding for a border wall Sunday in a letter to congressional leaders, demanding $5.7 billion for construction of a barrier as the partial government shutdown heads into its third week after weekend talks.

The wall is “central to any strategy,” wrote Russell Vought, acting director of the Office of Management and Budget, in asking for funds for “234 miles of new physical barrier.”

But the two-page letter, which was obtained by The Washington Post, also provided new details on Trump’s position, which has largely consisted of ultimatums and tweets amid stalled negotiations with Democrats, by listing funding requests for his immigration agenda across the federal government.

Trump advisers said Sunday that the administration wrote the letter after Democratic congressional aides asked Vice President Mike Pence, who led the weekend discussions at the White House, for specifics on budget estimates for the Trump administration’s priorities so the negotiations could advance this week.

“During our meetings with congressional staff this weekend, we made it clear that we have a crisis on our southern border, and we outlined the president’s plan to secure our border, build a wall and protect the American people,” Pence said in a brief interview. “It’s time for the Democrats to start negotiating.”

Senior administration officials described the letter as a flicker of progress, in particular the request for “an additional $800 million to address urgent humanitarian needs” and unaccompanied migrant children arriving at the border, an issue they said Democrats have made a priority during the talks. The officials also said the letter’s formal call for a “steel barrier” rather than a massive concrete wall – as Trump long promised – was another notable, if minor, development.

Still, both sides acknowledged that they remained far apart late Sunday, and while Democrats may be interested in negotiating a broader immigration deal that includes humanitarian funding, they have refused to do so unless the government is reopened – and House Speaker Nancy Pelosi, D-Calif., has called the wall an “immorality.”

Democrats largely reacted to the letter with a shrug, and several senior aides described the letter as a summary of the weekend meetings rather than a breakthrough. “The Republicans remain boxed in with the wall,” said one aide who was not authorized to speak publicly. “We can’t discuss everything else until the government reopens.”

The administration has also signaled that it would be willing to restore some version of an Obama-era program that allowed children in Central America to apply for U.S. asylum in their home countries, according to an official with knowledge of the proposal. The Central American Minors program, or CAM, was established during a 2014 border crisis, when unaccompanied minors were arriving in unprecedented numbers, often assisted by smugglers.

Trump canceled the program in 2017.

Restoring it has been a Democratic priority, but in exchange, the administration said it wants changes to laws that protect underage trafficking victims, so as to ease restrictions on the government’s ability to deport teenagers and children.

Earlier Sunday, Trump met with White House staffers at Camp David, where the president’s long-promised border wall was among the topics on the agenda.

The meeting came one day after Pence, top White House officials and senior congressional aides emerged empty-handed after more than two hours of negotiations on ending the stalemate.

“We’re looking at a national emergency because we have a national emergency,” Trump told reporters outside the White House upon returning Sunday evening. Before departing in the morning, he said he may act unilaterally to secure wall funding “depending on what happens over the next few days.”

In a bid to force Democrats’ hand, Trump has said he is considering declaring an emergency to begin wall construction without congressional approval. The legality of such a move is unclear, however, and the president would almost certainly face immediate legal challenges in the courts.

Trump also said Sunday that he understood the predicament facing hundreds of thousands of federal workers who are not receiving their paychecks.

“I can relate, and I’m sure the people who are on the receiving end will make adjustments; they always do,” Trump said. He claimed that “many of those people agree with what I’m doing”: refusing to reopen the government without obtaining funding for his long-promised border wall.

And he further backed away from the notion of a concrete wall, telling reporters that he has informed his staff to now say “steel barrier.” During the 2016 campaign, Trump often pledged to build a concrete wall, but on Sunday, he argued that steel slats “will be less obtrusive and stronger.”

Democrats on Sunday “pleaded again for the White House to change course and reopen government” by backing funding measures that have been passed by the House and have bipartisan support in the Senate, but Pence “said the president would not do that,” according to an official who was not authorized to speak publicly about the talks.

No further meetings have been scheduled.