White House chief of staff Mick Mulvaney listens as President Donald Trump speaks during a Cabinet meeting at the White House in Washington, Jan. 2, 2019. Credit: Evan Vucci | AP

WASHINGTON — President Donald Trump will secure the U.S. border with Mexico “with or without Congress,” acting White House chief of staff Mick Mulvaney said Sunday, as negotiations over Trump’s long-sought border wall begin anew.

In an interview on “Fox News Sunday,” Mulvaney declined to say whether Trump would accept less than the $5.7 billion in funding he has demanded for the wall. But he maintained that Trump is ready to use emergency powers to secure the border if Democrats continue to balk at his demands.

Trump’s obligation is to defend the country, Mulvaney said, “and he’ll do it either with or without Congress.”

The partial government shutdown, which was the longest in U.S. history, ended on Friday with Trump agreeing to temporarily reopen the government without any money for his border wall.

But a new crisis looms, as the deal provided funding only through Feb. 15. A bipartisan, bicameral committee has been charged with negotiating an agreement on border security as part of the deal, and a stalemate could trigger another shutdown in the coming weeks.

Mulvaney said that if the legislation Congress sends to Trump’s desk is unsatisfactory, Trump could veto it, which would result in another shutdown.

“Yeah. I think he actually is,” Mulvaney said on CBS’ “Face the Nation” when asked whether Trump is prepared to bring about a shutdown next month.

Some conservatives swiftly rebuked Trump for agreeing to reopen the government last week without wall funding. But Mulvaney dismissed those critiques on Sunday.

“Ultimately he’ll be judged by what happens at the end of this process, not by what happened this week,” Mulvaney said on Fox.

Trump argued Sunday that illegal immigration was costing the country tens of billions of dollars a month, although it was not clear on what data he was basing his estimate.

“We are not even into February and the cost of illegal immigration so far this year is $18,959,495,168,” he tweeted. “Cost Friday was $603,331,392.”

Trump has previously claimed that the cost of illegal immigration is more than $200 billion a year, without providing any evidence for those claims.

Roughly 11 million people are estimated to be living in the United States without documentation. But on Sunday, Trump challenged that number, tweeting that “there are at least 25,772,342 illegal aliens, not the 11,000,000 that have been reported for years, in our Country. So ridiculous! DHS”

Asked on “Face the Nation” about that number, Mulvaney said he did not know where Trump was getting his information. But he argued that the figure “has to be larger than 11 million” because of the numbers of migrants who continue to cross into the United States each month.

“I think that number was accurate a couple of years ago. We know that it’s going up,” Mulvaney said.

As the negotiations begin anew, lawmakers from both parties stuck to their positions Sunday, with Republicans echoing Trump’s call for a wall and Democrats rejecting the possibility.

“I don’t support any wall funding, but I do support border security,” Rep. Adam Schiff, D-California, said on ABC’s “This Week.” “And you know, the important thing, I think, to remember here is, Democrats and Republicans can not only reach an agreement on border security, we already have multiple times. … The only thing that got in the way was the president was frightened off by Ann Coulter and Rush Limbaugh.”

Schiff was referring to legislation last year that passed the Senate but was scuttled at the last minute after Trump, amid pressure from conservative pundits, made an abrupt reversal and announced his opposition.

In an appearance on CNN’s “State of the Union,” Sen. Marco Rubio, R.-Florida, said that he believes Trump is “willing to do something reasonable” for people who are in the United States with temporary protected status or through the Deferred Action for Childhood Arrivals program, or DACA, but that it is being held up by the ability to get an agreement on border security.

“I hope that people will separate the tactics from the policy, because I think the policy is reasonable and solid,” he said.