President Donald Trump will declare a national emergency to fund his planned border wall with Mexico, the White House says.
He is to sign a border security bill to avert a government shutdown – but also act to bypass Congress and use military funds for the wall, a statement said.
Congress must first pass the bill before it is signed by the president.
Building the wall was a key election promise but Mr Trump has so far been unable to get the necessary funding.
“The President is once again delivering on his promise to build the wall, protect the border, and secure our great country,” White House Press Secretary Sarah Sanders said in a statement on Thursday.
She added he would “take other executive action – including a national emergency – to ensure we stop the national security and humanitarian crisis at the border”.
The compromise legislation includes $1.3billion funding for border security, including physical barriers, but it does not allot money towards Mr Trump’s wall.
When Mr Trump warned that he might declare a national emergency over his wall earlier this year, some Republicans argued it would only set a dangerous precedent.
Speaking on the Senate floor on Thursday, however, party leader Mr McConnell indicated his support for the move, saying the president was taking action with “whatever tools he can legally use to enhance his efforts to secure the border”.
The Senate has passed the border security bill, which is now expected to go to the House of Representatives by this evening local time.
Speaker of the House Nancy Pelosi has already suggested a legal challenge from Democrats should the president make an emergency declaration.
“We will review our options and prepare to respond to it,” she told reporters on Thursday.
“I know the Republicans have some unease about it, no matter what they say.
“If the president can declare an emergency on something that he has created as an ’emergency’, an illusion that he wants to convey, then think of what a president with different values can present to the American people.”