U.S. President Donald Trump and congressional leaders agreed Friday to reopen the government for three weeks without providing the president with the $5.7 billion he has been seeking for a border wall with Mexico.

Trump announced the deal at the White House, saying it is a bid to allow time for negotiations to take place on the funding he is seeking and which Democrats continue to oppose. 

The funding will run through Feb. 15 -- 21 days from now -- at which point Trump said if he does not get the funds he is seeking, the government will either shut down or he will use emergency powers to build his wall. 

"We really have no choice but to build a powerful wall or steel barrier," Trump said. 

"Over the next 21 days, I expect that both Democrats and Republicans will operate in good faith. This is an opportunity for all parties to work together for the benefit of our whole beautiful, wonderful nation," he added.

Massive flight delays were reported ahead of the president's announcement, prompted by staff shortages of unpaid employees who called out sick on day 35 of the government shutdown, having missed a second paycheck this month. Delays of an hour and a half were reported at New York's LaGuardia International Airport and New Jersey's Newark Liberty International Airport.

Roughly 800,000 federal workers have been working without pay if their services are deemed essential or have been forced to stay home from their jobs without compensation during the shutdown which is, by far, the longest in history.

Trump demanded any bill to reopen the government include funding to build his separation barrier, but as the shutdown neared the start of its sixth week, he agreed to a stopgap bill lacking the money to fund his signature campaign promise, which he vowed Mexico would pay for. 

A bipartisan conference with lawmakers from both chambers is being formed to address border security and related issues ahead of the Feb. 15 deadline. But while Democrats voiced openness to increasing technologies and other efforts to secure the border, they remained resolute in opposition to a wall.

"We in Congress will roll up our sleeves," Senate Minority Leader Chuck Schumer pledged on the Senate floor. "We don't agree on some of the specifics of border security. Democrats are against the wall. But we agree on many things such as the need for new technology and the need to strengthen security at our ports of entry.

"That bodes well for coming to an eventual agreement," he added. 

Trump is expected to sign the short-term spending bill later Friday after it clears Congress. But he is unlikely to have his State of the Union address on the initially agreed upon Jan. 29 date. 

House Speaker Nancy Pelosi, who has to allow legislation to schedule the nationally-television speech to reach the House floor, said her and the president have yet to agree on a date. She had previously called off the speech during the shutdown, vowing it would not take place as long as federal agencies were shuttered. 

"The State of the Union is not planned now," Pelosi told reporters at the Capitol. "What I'd said to the president is when the government is opened, we would discuss a mutually agreeable date, and I'll look forward to doing that."