WASHINGTON – President Donald Trump would "totally be willing" to shut down the federal government if Congress does not approve $5 billion for construction of a wall along the U.S.-Mexican border, he said during an Oval Office interview with Politico.

The president has pushed congressional leaders to approve the funding for his long-promised wall – which he had vowed would be paid for by Mexico – as the threat of a partial government shutdown looms.

This year, Democrats and Republicans reached a deal to fund most of the government into 2019, but funding for some agencies, including the Department of Homeland Security, is set to expire Dec. 7. Trump also threatened a shutdown during the negotiations in July.

Trump told Politico that the $5 billion he demands would be only for the wall and that the "number is larger for border security" overall.

House Republicans backed Trump's call for $5 billion; the House Appropriations Committee approved the spending in July. A bipartisan Senate bill earmarked $1.6 billion for the wall.

More:Trump threatens to close the border – permanently

More:House approves spending bill to avert government shutdown but delays fight over border wall

Although Republicans still control both the Senate and House, GOP leaders said Democrats will be to blame if a deal on border security is not struck.

House Majority Whip Steve Scalise, R-La., wondered if Democrats are "going to shut down the government because they don’t want to keep America safe?"

"I'm glad that President Trump is following through on his commitment to keep this country safe. He needs $5 billion to make sure he can follow through on that promise, and we need to be there for him and see that this gets done," Scalise said after a White House meeting Tuesday.

"We need Democrat votes to have a wall," Trump told The Washington Post, indicating he had a backup plan if the funding fell through.

"Now, if we don’t get it, will I get it done another way? I might get it done another way. There are other potential ways that I can do it. You saw what we did with the military, just coming in with the barbed wire and the fencing and various other things," he told the Post.

Democrats pushed back, noting the Republican hold of Congress and the White House.

"If there's any shutdown, it's on President Trump's back," Senate Minority Leader Charles Schumer, D-N.Y., said Tuesday.

"Stick to the $1.6 billion," he said.

Schumer indicated that Democrats might block passage of the spending bill unless legislation is passed that would protect special counsel Robert Mueller's investigation from White House interference.

"I didn’t know Robert Mueller needed protection," House Majority Leader Kevin McCarthy, R-Calif., said. "But I do know the southern end of our country needs protection."

Although the president said he does not do anything "just for political gain," he believes that when it comes to border security, "politically speaking, that issue is a total winner."

"People look at the border, they look at the rush to the police, they look at the rock throwers and really hurting three people, three very brave Border Patrol folks – I think it's a tremendous issue, but much more importantly is really needed," he told Politico.

Trump referred to a confrontation at the U.S.-Mexican border near Tijuana where members of a Central American immigrant caravan clashed with border authorities Sunday.

Customs and Border Protection Commissioner Kevin McAleenan said four officers were struck with rocks before they fired tear gas at the immigrants trying to rush the San Ysidro Port of Entry. McAleenan said the officers "were wearing protective gear and did not suffer serious injuries."

More:Customs and Border Protection says Tijuana tear gas incident is under internal review

More:Families still being separated at border – months after Trump’s ‘zero tolerance’ policy reversed

Contributing: Bart Jansen and Alan Gomez, USA TODAY; The Associated Press