By Michael Hernandez

WASHINGTON

U.S. President Donald Trump will sign a compromise spending bill to avert another partial government shutdown and will declare a national emergency to build a U.S.-Mexico border wall, the White House said Thursday. 

Spokeswoman Sarah Sanders said on Twitter that Trump would deliver on his signature campaign promise through executive actions, including the emergency declaration, even as his declaration is highly likely to result in a bevy of legal challenges. 

The bill includes just short of $1.4 billion in funding for 55 miles (89 kilometers) of additional border wall fencing. That is far short of the $5.7 billion Trump had been seeking to fund the separation barrier he vowed on the campaign trail to have Mexico pay for. 

Shortly after Sanders made the announcement, the Senate passed the bill in an overwhelming 83-16 vote. 

The Democratic-controlled House is expected to vote on the bill Thursday evening.

Asked about a possible Democratic legal challenge to Trump's looming emergency declaration, House Speaker Nancy Pelosi said she "may" take the action, hinting strongly that she would do so.

"It's important to note that when the president declares this emergency, first of all, it's not an emergency what's happening at the border – It’s a humanitarian challenge to us," she said. 

Moreover, Pelosi said Trump is attempting to circumvent Congress' constitutional authority, particularly its power to make appropriations.

"The precedent that the president is setting here is something that should be met with great unease and dismay by the Republicans, and of course we will respond accordingly when we review our options," she added. 

But beyond politics, an emergency declaration is likely to face legal challenges from land owners whose property Trump would have to expropriate to build his separation barrier. 

Asked if Trump is prepared for potential legal challenges, Sanders said he is, but "there shouldn't be" any.

"The president's doing his job. Congress should do theirs," she told reporters at the White House.

Additional details on the declaration are expected later, Sanders said, but declined to say when they would be made available.