The bipartisan legislation, passed by the Republican-led Senate on Thursday before going to the Democratic-led House of Representatives for final congressional approval, denied Trump the funds he had demanded for a border wall, one of his central 2016 campaign pledges.

In a move that could infringe upon the power of Congress over the national purse strings and plunge Trump into an extended court battle with lawmakers over constitutional powers, White House spokeswoman Sarah Sanders said Trump will declare an emergency.

Trump’s administration has suggested he could use national emergency powers to redirect money already committed by Congress for other purposes toward paying for his wall.

“President Trump will sign the government funding bill, and as he has stated before, he will also take other executive action – including a national emergency – to ensure we stop the national security and humanitarian crisis at the border,” White House spokeswoman Sarah Sanders said on Thursday.

But the top Democrat in Congress immediately denounced the president’s move. Asked by reporters if she would file a legal challenge, House of Representatives Speaker Nancy Pelosi said, “I may, that’s an option.”

The top Senate Democrat, Chuck Schumer, accused Trump of a “gross abuse of the power of the presidency.”

Senate Majority Leader Mitch McConnell, a Republican, said he will support Trump on an emergency declaration.

Congressional aides said House Democrats were expected to file a lawsuit when Trump declares a national emergency in order to protect the House’s constitutional powers to decide how US taxpayers’ money is appropriated.

A source familiar with the situation said that the White House had identified $US2.7 billion in funds previously provided by Congress that could be redirected to barrier funding as part of a national emergency.

The Senate passed the federal spending legislation by a margin of 83-16. The House was expected to take it up later on Thursday. The measure would provide more than $US300 billion to fund the Department of Homeland Security and a range of other agencies through September 30.

The legislation includes $US1.37 billion in new money to help build 89km of new border barriers.

Funding for those agencies is due to expire on Friday, which would trigger another partial federal shutdown on Saturday if Congress and Trump do not act quickly.

Pelosi accused Trump of doing “an end-run” around Congress and around the Constitution’s separation of powers that gives Congress, not the president, federal spending authority.

“It’s not an emergency, what’s happening at the border. It’s a humanitarian challenge to us,” Pelosi said.

“If the president can declare an emergency on something that he has created as an emergency – an illusion that he wants to convey – just think of what a president with different values can present to the American people.”

She specifically cited US gun violence as an emergency.

Trump triggered a 35-day-long shutdown of about a quarter of the federal government with his December demand for $US5.7 billion to help build a portion of the wall.

– Reuters