Senate Majority Leader Mitch McConnell disclosed Trump's intentions to declare a national emergency, shortly before the Senate approved the legislation that would provide funding for several major US agencies through September and include the barrier money. The 1976 law that permits this step, the National Emergencies Act, gives the president a wide scope in defining exactly what qualifies as an "emergency".
For President Trump's impending national emergency, Ferguson says his legal team "has been reviewing this issue for some time".
An emergency declaration would allow Trump to divert funds appropriated for other purposes to build the wall.
After weeks of brandishing the threat of invoking a national emergency, President Trump is going ahead and declaring one. It is expected to pass both chambers easily.
Top Senate Democrat Chuck Schumer called the bill a "reasonable compromise" and Republicans literally prayed on Thursday afternoon that Trump would have the "wisdom" to sign off on the legislation in order to avoid another shutdown.
Trump's assent would end a raucous legislative saga that commenced before Christmas and was ending, nearly fittingly, on Valentine's Day.
Trump began weighing whether to declare a national emergency after Democrats refused to cave to his demand for $5.7bn in funding for the wall, prompting a 35-day government shutdown - the longest in U.S. history.
With polls showing the public blamed him and GOP lawmakers, Trump folded on January 25 without getting any of the wall funds.
On Monday, as congressional leaders announced a compromise that didn't include wall funding, Trump declared in front of a rally of supporters that he was going to get the wall built one way or the other. Speaker Nancy Pelosi said Thursday the House of Representatives might sue, and some Democratic state attorneys general said their states would, too. That sentiment weakened Trump's hand and fueled the bipartisan deal, a pact that contrasts with the parties' still-raging differences over health care, taxes and investigations of the president. The compromise provides for $1.375 billion for 55 miles of border fencing, which is less than the deal past year that forced the shutdown.
Trump had demanded $5.7 billion to start building more than 200 miles of wall.
Many have warned that they have no idea from where Trump will draw the funding.
The deal also allocates US$563 million to hire more immigration judges to address a massive case backlog, and US$415 million for humanitarian operations at the border.
Late on Wednesday, negotiators put the finishing touches on the legislation that would provide more than $300 billion to fund the Department of Homeland Security and a range of other federal agencies through September 30, the end of the current fiscal year. But Graham also told reporters Trump would then look elsewhere to find more money to build the wall and was "very inclined" to declare a national emergency to secure the funds.
That will likely trigger a long legal fight possibly stretching into Trump's 2020 re-election bid, and embolden critics who already accuse him of authoritarian tendencies and unpredictable swerves in policy-making. Trump's determination to secure funding for the border wall and the refusal by Democrats led to the first partial government shutdown.
White House officials have been digesting the text since early morning and have briefed the President as they go along. The bill has restrictions on where the fencing can be built, including explicit protections for sites like a butterfly refuge in the Rio Grande Valley. The chairman of the conservative House Freedom Caucus, Mark Meadows, R-N.C., has criticized the agreement as failing to meet Trump's border demands. "He's trying an end-run around Congress in a desperate attempt to put taxpayers on the hook for it".
"Mexico wouldn't pay for @realDonaldTrump's wall". "Donald Trump's ridiculous wall is not an emergency".