The president’s concession came as the effects of the shutdown, which stretched into its 35th day on Friday, started to dramatically ramp up. As the shutdown’s fifth week came to a close, the East Coast was riven with airline delays and federal workers missed their second paycheck.

It’s unclear whether divided lawmakers will be able to reach an agreement in the coming weeks that can satisfy the president’s demands for a wall. In his Friday speech, Trump threatened to declare a national emergency if the negotiations fail.

“As everyone knows, I have a very powerful alternative, but I didn’t want to use it at this time,” Trump said. “Hopefully it will be unnecessary.”

The president said that he plans to make sure the 800,000 federal workers who have gone without a paycheck for more than a month will receive back pay “very quickly or as soon as possible,” likely within four or five days, according to one senior administration official.

Congressional leaders immediately announced their support for the plan.

“The longest shutdown in American history will finally end today,” Senate Minority Leader Chuck Schumer said on the floor Friday afternoon.

Trump’s announcement temporarily diverted cable news coverage of the blockbuster arrest of longtime Trump associate Roger Stone, a revelation that dominated Friday morning headlines even as White House aides and the president’s legal team sought to downplay its significance.

Meanwhile, Trump’s decision came under fire from some on the right. “Good news for George Herbert Walker Bush: As of today, he is no longer the biggest wimp ever to serve as President of the United States,” conservative pundit Ann Coulter tweeted.

Yet, some of Trump’s conservative allies sought to counter those who argued Trump had capitulated. “The president is sticking by his commitment to keep our communities safe and has assured me that nothing will deter him from accomplishing that goal. His resolve remains steadfast,” said North Carolina Rep. Mark Meadows (R-N.C.), who regularly speaks with Trump.

The lengthy shutdown has infuriated many on Capitol Hill, who have been exasperated by an unpredictable and inconsistent president.

“He shut it down. Was it worth it? It’s the most stupid shutdown I’ve ever seen in my life,” said Sen. Jon Tester (D-Mont.), adding, “Let’s hope there can be honest negotiations, not moving the goal posts.”

Senate Majority Leader Mitch McConnell met with Schumer on Thursday afternoon, setting up the potential to reopen the government. McConnell briefed Republicans on the plan at lunch on Friday, then senators in attendance watched the president’s address themselves. Afterward McConnell said Congress will concentrate on border security in the next three weeks and that “negotiations on DHS will be prioritized over consideration of any other funding bills.”

Senators in both parties were skeptical that Congress will end up in a different place in three weeks. “There isn’t any insurance policy on that. You can’t,” said Sen. Kevin Cramer (R-N.D.), who said people should take Trump’s national emergency threat seriously. “I’m amazed at his patience.”

But Democratic leaders tried to put an optimistic spin on the upcoming negotiations.

“Democrats are firmly against the wall,” Schumer said. “But we agree on many things ... and that bodes well for finding an eventual agreement.”

“I do have to say that I’m optimistic,” echoed House Speaker Nancy Pelosi.

After passing the bill to reopen the government, the Senate named negotiators for an upcoming conference on border security: Senate Appropriations Chairman Richard Shelby (R-Ala.) and GOP Sens. Shelley Moore Capito of West Virginia, Roy Blunt of Missouri and John Hoeven of North Dakota, as well as Democrats Patrick Leahy of Vermont, Dick Durbin of Illinois and Jon Tester of Montana.

The agreement was the product of negotiations between the Senate’s top leaders, McConnell and Schumer, who met on Thursday following the failure of two long-shot measures to reopen the government. During the meeting, McConnell and Schumer discussed several options to temporarily reopen the government: One was a pro-rated “down payment” on the wall, another was larger funding bill for other departments beyond DHS, aides said. Both were deemed unrealistic.

Schumer insisted that Democrats wouldn’t support wall funding. Schumer then countered with a proposal to first reopen the government, then move to negotiations on border security. McConnell said he’d take that proposal to the White House. The two Senate leaders kept in touch on the phone throughout the day on Friday.

Trump’s decision to back a measure to temporarily open the government while negotiations continue comes one day after the White House urged Republicans to reject a nearly identical proposal put forward by Senate Democrats. Some in the White House, including the president’s son-in-law and senior adviser Jared Kushner, had been hoping to strike a wide-ranging immigration compromise as part of the talks to reopen the government, a prospect that few on Capitol Hill believed was realistic.

On Thursday, six Republicans voted to support the Democratic plan to reopen the government through Feb. 8, sending an unmistakable signal to the White House that lawmakers of both parties were eager to strike a deal to end the stalemate. Just one Senate Democrat voted for Trump’s proposed plan to trade temporary legal protection for some undocumented immigrants for funding for a southern border wall

Trump has repeatedly rebuffed calls to reopen the government without money for the wall . During a meeting last week with a bipartisan group of House lawmakers, Trump worried that he might not be able to get funding for his border wall if he agreed to reopen the government while negotiations continue.

“If I open it up, it’s going to be hard to shut down again,” Trump said, according to a person in the room.

But Trump’s allies in Congress urged him to reconsider.

Republican Sen. Lindsey Graham, who met with McConnell on Friday and spoke to Trump on Thursday, said earlier in the day that a series of airport delays that have rippled across the country are “signs of things to come” during the shutdown. Graham has counseled the president to endorse the idea of briefly reopening the government to have a three-week immigration debate.

On Friday morning, a wave of airport delays hit the East Coast, which some saw as a visible sign that pressure was mounting on the White House to end the shutdown.

“The President has been briefed and we are monitoring the ongoing delays at some airports. We are in regular contact with officials at the Department of Transportation and the FAA,” White House press secretary Sarah Huckabee Sanders said earlier Friday.

Jake Sherman, Gabby Orr, Anita Kumar, John Bresnahan, Marianne Levine and Eliana Johnson contributed to this story.