WASHINGTON (Reuters) - U.S. President Donald Trump said he would “totally be willing” to shut down the federal government unless Congress authorized $5 billion to fund his long-promised wall along the U.S. border with Mexico, according to a Politico interview published on Wednesday.

U.S. President Donald Trump speaks to reporters before he boards the Marine One helicopter to begin his travel to Mississippi from the White House in Washington, U.S. November 26, 2018. REUTERS/Jonathan Ernst

Trump also told the news outlet that the suggested $5 billion would pay for the physical barrier alone, and that additional funding would be needed for other border security measures.

The president has not followed through on previous threats to shut down the U.S. government over funding for the border wall, a signature promise of his 2016 election campaign.

But with his fellow Republicans set to lose control of the House of Representatives in January after the recent midterm elections, it is not clear if this time Trump will back down.

Illegal immigration was a central theme of Trump’s presidential bid, and he repeatedly invoked the issue ahead of the Nov. 6 midterm elections as a caravan of migrants from Central America made their way toward the United States and deployed some 5,800 U.S. troops to the border.

He has also threatened to completely shut down the border, a warning Mexican Foreign Minister Luis Videgaray rejected on Wednesday.

The Trump administration’s use of tear gas against Central American migrants who rushed the border last weekend drew rebuke from Democrats and other critics. The Department of Homeland Security defended Border Patrol agents’ actions while Mexico urged an investigation into the incident.

U.S. lawmakers must act to pass a spending bill by Dec. 7 to fund some government agencies, including the Department of Homeland Security which oversees borders and immigration.

Republicans will maintain their control of the Senate next year but still need some Democratic support to pass spending legislation.

The head of the Senate Homeland Security committee chairman, Republican Ron Johnson, said Trump “deserved to have better barriers funded” but noted that most government funds had already been appropriated and that most security spending would continue under emergency provisions.

“It’s very difficult to shut down the government,” Johnson told Fox News.

His Republican colleague, Orrin Hatch, told NBC News he had “mixed emotions” but that both sides should be able to find a solution.

U.S. House Speaker Paul Ryan said the House version of spending legislation does contain Trump’s requested $5 billion but acknowledged that Democrats, who have refused to support Trump’s border wall but support other border security measures, have a say.

“What we’ll have to do is come together,” he told reporters.

Trump told Politico the political battle over the border was a “total winner” for his party even as he said he was not taking action “just for political gain.”

In a separate interview with The Washington Post on Tuesday, Trump said that if Congress does not fund the wall he might try to get it done another way and referred to the deployed troops’ work installing “barbed wire and fencing and various other things.”

Last week, U.S. Defense Secretary Jim Mattis said there could be new troops at the border in the future with new missions. A U.S. official, speaking on the condition of anonymity, said the border mission could be extended beyond the current authorization through Dec. 15.

Trump also told Politico that he saw little need to work with Congress over immigration reforms to address the roughly 700,000 so-called Dreamers, young adults who were brought to the United States illegally as children, and would instead see how court challenges play out.