WASHINGTON — President Donald Trump plans to declare a national emergency to fund his controversial border wall, the White House said on Thursday, a move that alarmed US lawmakers shortly before they passed legislation to avert a government shutdown.

Trump has signaled he will sign the massive spending measure keeping federal agencies operational through September 30.

But it does not specifically fund a wall on the US-Mexico border, and Trump’s emergency declaration would help him bypass Congress to locate and redirect billions of dollars in funding to build it.

Trump will take the action "to ensure we stop the national security and humanitarian crisis at the border", White House Press Secretary Sarah Sanders said shortly before the Senate passed the spending bill.

The House of Representatives followed suit hours later, and Trump has until a midnight Friday deadline to sign it and prevent the government from going into shutdown for the second time this year.

Signing the spending bill would bring an end to a rolling, two-month battle over government funding. But by declaring an emergency, Trump opens a new confrontation -- and creates some of the riskiest legal peril of his term.

House Speaker Nancy Pelosi, Trump’s Democratic nemesis in Congress, said members of her caucus were "reviewing our options" about how to respond to Trump’s move.

"Declaring a national emergency would be a lawless act, a gross abuse of the power of the presidency and a desperate attempt to distract from the fact that President Trump broke his core promise to have Mexico pay for his wall," Pelosi and Senate Minority Leader Chuck Schumer said in a statement.

Senate Majority Leader Mitch McConnell said he backs the president, but several others in the Republican camp have expressed deep reservations.

"I have concerns about the precedent that could be set with the use of emergency action to re-appropriate funds," veteran Republican Senator Chuck Grassley said in a statement.

Senator Susan Collins said it "would be a mistake on the part of the president" to declare such an emergency, warning it would "undermine" lawmakers’ all-important role as financial appropriators.

Many lawmakers have said they have no idea from where Trump will draw the funding. Democrats in particular have signaled that the move would open the door to future presidents declaring emergencies on various topics, from gun violence to climate change to the opioid crisis. — AFP