“If he has to give up a concrete wall, replace it with a steel fence in order to do that so that Democrats can say, ‘See? He’s not building a wall anymore,’ that should help us move in the right direction,” Mulvaney said in an interview airing Sunday on NBC’s “Meet the Press,” according to a transcript provided by the network.

The partial government shutdown, entering its 16th day, dominated the discussions among government officials on Sunday morning news programs, including Mulvaney and Sarah Huckabee Sanders, Trump’s top spokeswoman as well as lawmakers from both sides of the aisle.

A delegation of top White House aides led by Vice President Mike Pence will meet again with congressional staff on Sunday after a two-and-a-half hour discussion Saturday was unable to forge a deal and Trump said on Twitter that “not much headway” was made.

Democrats have insisted that Trump support reopening the government while the negotiations on the border wall continue, and while they’ve supported funding for border security, they have opposed money for the U.S.-Mexico border wall that was Trump’s signature campaign promise.

The Democrats asked for a formal budget justification for the administration’s position in order to determine what the White House’s request is, said a person familiar with the discussion.

In his interview on NBC, Mulvaney conceded that Trump, who said last month he would “take the mantle of shutting down” the government over border security, is losing the fight over public opinion over the shutdown and accused Democrats of trying to stall.

“I really do firmly believe they think they’re winning the PR battle and they’re willing to drag this out because they think it hurts the president,” Mulvaney said.

Trump has said contradictory things in recent weeks about what would constitute a wall. The president tweeted on Dec. 18 that “we are not building a Concrete Wall, we are building artistically designed steel slats, so that you can easily see through it.”

After former Chief of Staff John Kelly suggested in an interview with the Los Angeles Times published Dec. 30 that the idea of a concrete wall had been nixed long ago and “to be honest, it’s not a wall,” Trump tweeted the next day that “an all concrete Wall was NEVER ABANDONED, as has been reported by the media.”

Sunday’s negotiating session will follow a two-and-a-half hour meeting Saturday between Pence, senior Trump adviser Jared Kushner, Homeland Security Secretary Kirstjen Nielsen and staff for House and Senate leadership.

Trump said Friday he could declare a national emergency to circumvent Congress and build the wall, though budget experts said Congress would still need to allocate the funds. His comments came after he met with House Speaker Nancy Pelosi and Senate Minority Leader Chuck Schumer. The Democrats, who think the proposed wall is a waste of money, said the meeting was contentious, though Trump said it was productive.

Meanwhile, the shutdown is having wide-reaching effects. Airlines can’t get permission to add new planes to their fleets, mortgage lenders can’t verify the income of borrowers and the Food and Drug Administration can’t accept many new drug applications.

Trump was tweeting about the wall early on Sunday, quoting past comments in support of a barrier by former president Barack Obama, whose name he misspelled, and Senator Hillary Clinton and insisting the wall will end illegal border crossings and and crime.

“The only reason they do not want to build a Wall is that Walls Work!” Trump tweeted.

Trump plans to travel to the Camp David presidential retreat in Maryland on Sunday for what he termed “meetings on Border Security and many other topics” with senior White House staff.