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WASHINGTON — President Donald Trump plans to declare a national emergency after Congress passed a government spending deal that provides further funding for border security, the White House announced Thursday.

A Trump administration official confirmed Thursday night that the president will announce around $8 billion for a border wall under executive actions, part of which will be the emergency declaration.

That figure includes $1.375 billion in the spending bill for fencing in Texas; $600 million from the Treasury Department’s drug forfeiture fund; $2.5 billion from a Defense Department drug interdiction program; and $3.5 billion from a military construction budget under an emergency declaration by the president.

Trump will hold an event in the Rose Garden about the border at 10 a.m. Friday, the White House said.

"President Trump will sign the government funding bill, and as he has stated before, he will also take other 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 said in a statement Thursday afternoon.

Shortly after the White House's announcement, the Senate voted 83-16 to pass the government spending deal, which would provide further funding for border security but no money for Trump's border wall.

The bill, negotiated by a bipartisan group of congressional leaders, passed the House on Thursday night, a day before the deadline of Friday night to prevent another partial government shutdown. The final vote was 300-128.

In declaring a national emergency, Trump plans to use funding from multiple parts of the federal government to extend border barrier mileage, most notably the Defense Department, two senior administration officials and a congressional aide told NBC News.

House Speaker Nancy Pelosi, D-Calif., said Thursday that if Trump declares a national emergency, Democrats could consider legal action to stop him.

"That's an option, and we'll review our options," Pelosi said. "But 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. The president has tried to sell a bill of goods. But putting that aside, just in terms of the president making an end run around Congress, here he said let us respect what the committee will do, then walks away from it.

Pelosi and Senate Minority Leader Chuck Schumer, D-N.Y., released a joint statement after the White House announcement vowing to defend the constitutional separation of powers.

"Declaring a national emergency would be a lawless act, a gross abuse of the power of the presidency and a desperate attempt to distract from the fact that President Trump broke his core promise to have Mexico pay for his wall," their statement said.

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Several Republican lawmakers joined Democrats in criticizing Trump's decision.

"I think it's a dangerous step," said Sen. John Cornyn, R-Texas. "One, because of the precedent it sets. Two, because the president is going to get sued and it won't succeed in accomplishing his goal, and three, because I think Mrs. Pelosi will then introduce a resolution which will pass the House, then come over here and divide Republicans. So to me, it strikes me as not a good strategy."

While Cornyn didn't specify what legislative action he meant, the National Emergencies Act, which gives presidents the power to declare national emergencies, specifies a process by which Congress can terminate such emergencies by joint resolution.

House Judiciary Committee Chairman Jerry Nadler, D-N.Y., said in a statement Thursday night that he would "fully support" the passage of such a resolution and intends "to pursue all other available legal options."

Rep. Cathy McMorris Rodgers of Washington, a former chairwoman of the House Republican caucus, also raised the separation of powers issue, questioning what actions a future Democratic president might take under that precedent.

"By circumventing Congress and Article I of the Constitution, President Trump is opening the door for any future president to act alone without Congressional approval," Rodgers said.

Republicans urge Trump's signature

Senate Majority Leader Mitch McConnell, R-Ky., announced earlier Thursday afternoon that Trump would sign the spending package that resulted from bipartisan negotiations over border security and also declare a national emergency to provide more funding for his proposed border barrier.

"I just had an opportunity to speak with President Trump, and he's prepared to sign the bill," McConnell said on the Senate floor. "He will also be signing a national emergency declaration at the same time."

Trump had said earlier in the day that he was still reviewing the bill. The president also had said he wasn't "happy" with the measure.

"Reviewing the funding bill with my team at the @WhiteHouse!" he tweeted Thursday afternoon ahead of the Senate vote.

In the morning, Republican senators said they "pray" that Trump signs it into law, averting another shutdown.

The 1,159-page bill would provide $1.375 billion for 55 miles of pedestrian and levee fencing in the Rio Grande Valley of Texas, significantly less than Trump's $5.7 billion request. It also would prohibit the use of a concrete wall or other Trump prototypes and specify that only "existing technologies" for fencing and barriers could be used.

Despite a 35-day government shutdown over $5.7 billion for a border wall, the president came out with a worse deal than he would have gotten had he backed the funding bill that lawmakers from both parties agreed to last June as part of the normal appropriations process. That bill included $1.6 billion in border funding — the original request by the Trump administration — and 65 miles of new border fencing.

In remarks on the Senate floor, McConnell defended the agreement, saying that "no side will view this as a perfect deal" but that it's "something both sides should view as an important step."

"And today, I hope we will vote to advance it," he said.

Senate Republicans had publicly urged Trump to sign the deal once it received congressional approval. NBC News reported this week that they expected the president to sign it.

After the Senate chaplain delivered the opening prayer on the Senate floor, Sen. Chuck Grassley, R-Iowa, chimed in: "I pray that the president will have wisdom to sign the bill so the government doesn't shut down."

Senate Appropriations Committee Chairman Richard Shelby, R-Ala., who helped negotiate the deal, said he had told Trump and Vice President Mike Pence that the bill should be viewed as a "down payment" to fund border security.

In addition to funding the Department of Homeland Security, the spending package would also fund eight other federal departments: Agriculture, Commerce, Housing and Urban Development, Interior, Justice, State, Transportation and Treasury.

Notably, the agreement would exclude an extension of the Violence Against Women Act, which Republicans wanted to include, but Democrats insisted on passing a more comprehensive reauthorization of the program later this year.

Democrats also pushed unsuccessfully to include a provision to provide back pay for federal contractors affected by the recent shutdown. Sen. Roy Blunt, R-Mo., told reporters Wednesday that Trump wouldn't sign the measure if the provision were included.