President Donald Trump will sign a funding bill to keep the government open and simultaneously declare a national emergency at the United States-Mexico border, an effort to bypass Congress to build his long-demanded wall, the White House announced Thursday.

Passed by the Senate Thursday afternoon, the bill would fund nine federal departments until the end of the fiscal year on Sept. 30 and avert another shutdown. The White House’s declaration comes a day before a short-term federal funding bill — which ended a 35-day partial government shutdown in January — was scheduled to expire.

The bill provides $1.375 billion to build 55 miles of new barriers along the border — far short of the $5.7 billion Trump initially demanded for 200 miles of wall. It will also fund 40,520 beds to detain immigrants entering or in the U.S. illegally.

The House is slated to vote on the legislation Thursday evening.

“President Trump will sign the government funding bill, and as he has stated before, he will also take another executive action — including a national emergency — to ensure we stop the national security and humanitarian crisis at the border,” White House press secretary Sarah Sanders wrote on Twitter. “The President is once again delivering on his promise to build the wall, protect the border, and secure our great country.”

What happens in a national emergency?

Under the National Emergencies Act of 1976, the president has the power to declare a national emergency, which would enhance the chief executive’s power in order to act quickly in a crisis.

However, the act does not provide a definition or requirements for a “national emergency.”

According to a December 2018 study from the Brennan Center, a non-partisan public policy and law institute, the declaration would provide Trump with more than 100 emergency powers, including the ability to shut down or take over radio stations, suspend American bank accounts, and waive a law prohibiting the testing of chemical and biological weapons on human subjects.

While some legal precedent points to allowing Trump to use a national emergency to build a border wall, the move will almost certainly incite a court battle, Elizabeth Goiten of the Brennan Center told the New York Times.

Under the National Emergencies Act, Congress can end a national emergency through votes in the House, Senate, and a signature from the president.

Given that the Senate is under Republican control, and overriding a veto requires two-thirds majority from both houses, this is considered an unlikely outcome.

Overall, 58 national emergencies have been declared since the act was passed, with 31 still in effect. George W. Bush issued several national emergency declarations in response to the Sept. 11, 2001, terrorist attacks, and Franklin D. Roosevelt declared a national emergency to authorize the interment of U.S. residents and citizens of Japanese descent during World War II.

Legislators slam emergency declaration

Lawmakers from both sides of the aisle promptly decried the possible declaration of a national emergency Thursday afternoon.

Democratic senators and presidential hopefuls Kamala Harris of California and Cory Booker of New Jersey, who launched his 2020 bid earlier this month, both quickly condemned the move, with Harris calling the border wall the “president’s vanity project.”

Meanwhile, Sen. Susan Collins (R., Maine) told reporters she thought calling a national emergency was “a mistake on the president’s part,” while Sen. Rand Paul (R., Ky.) called the legislation a “massive, bloated, secretive bill.”

Pelosi says she ‘may’ file legal challenge

Minutes after Sanders’ announcement, House Speaker Nancy Pelosi told reporters she “may” file a legal challenge against a declaration of a national emergency, but will consider all options.

House Democrats announced Thursday night that they were preparing a joint resolution disapproving Trump’s border wall, which is expected to easily clear the Democrat-controlled House and force Senate Republicans to vote on the divisive issue.

“This is a gross abuse of presidential power,” House Judiciary Committee Chairman Jerrold Nadler (D., N.Y.) told the Washington Post. “This is an attempt to overturn the basic constitutional doctrine of separation of powers. Congress has the power of the purse. It cannot be tolerated.”

Sanders told White House reporters that “we are very prepared (for legal challenges), but there shouldn’t be."

On Senate floor, McConnell says Trump will sign bill, declare emergency

The first indication of the president’s plans came from Senate Majority Leader Mitch McConnell (R., Ky.), who described what the Trump had told him on the Senate floor earlier Thursday.

“I’ve just had an opportunity to speak with President Trump...he has indicated he is prepared to sign the bill. He will also be issuing a national emergency declaration at the same time,” McConnell announced during a vote on the Senate floor.

Staff writer Rob Tornoe contributed to this story.