Democrats immediately sought to discredit Trump calling for a national emergency by suggesting that there is no "emergency" on the border, despite the hundreds of thousands of people who are apprehended every year illegally trying to enter the USA on the southern border.
What is a national emergency declaration?
Fortunately, there is a legal mechanism in place, although technically it's never been done before.
It's still unclear exactly what powers the president will cite to declare some form of national emergency.
Margaret L. Taylor, a former Democratic chief counsel and deputy staff director for the Senate Foreign Relations Committee, wrote in an article posted January 7 to Lawfare that Trump will face a challenge in convincing people that an emergency exists and that he is not abusing his power.
The administration has been eyeing several pots of money - including disaster funds, counter-narcotic accounts and military construction dollars - to fund the wall, according to congressional aides and White House officials.
The almost 1,200 page legislation would fund nine Cabinet departments and dozens of other agencies through September 30.
President Trump will declare a national emergency to free up funding for border security measures along the southern border, in addition to signing a compromise bill that doesn't include as much funding as he wanted.
As an example, the aides said there is funding for a medical facility at a USA base in Germany that has been partially built.
Monica Witt, former Air Force counterintelligence specialist, accused of spying for Iran
Later that year she worked with Individual A to make a video critical of the United States, and the two continued to communicate. In Iran, she has appeared to work at times to publish anti-American articles for the state-owned Press TV.
Mitch McConnell said he would be supporting the President's move. The House is scheduled to vote later in the evening.
The Senate passed the federal spending legislation by a margin of 83-16.
Republican supporters of the bipartisan agreement had stressed that it left Trump flexibility to take other measures to secure more funding for border barriers. "Trump just destroyed the U.S.A.", Coulter tweeted on Thursday afternoon.
Grassley has criticized the idea of Trump declaring an emergency to build his wall.
Mrs Pelosi added: "If the president can declare an emergency on something he has created as an emergency - an illusion that he wants to convey - just think what a president with a different set of values can present to the American people". On the conservative media tip, I want to explain Sean Hannity's advice to the president, because it's nearly remarkable.
Pelosi accused Trump of doing "an end-run" around Congress and around the Constitution's separation of powers that gives Congress, not the president, such authority as federal spending and declaring war.
Mr Trump will sign a border security bill to avoid a government shutdown after warning his wall was "very, very on the way".
A final Senate vote was to follow, and House Speaker Nancy Pelosi said her chamber would vote later Thursday.
She said: "We will review our options and prepare to respond to it".
However, there were a few last minute add-ons that Democrats managed to get into the legislation, including a $450 million budget to spend on humanitarian services for illegal immigrants.
The bill allocating just $1.3 billion for a barrier along the US-Mexico border - a far cry from the $5.7 billion requested by Trump - has been approved by the Senate and is now going through the House.