People look at the U.S. Capitol Christmas Tree on Dec. 23. The National Christmas Tree closed because of the government shutdown. (Sarah L. Voisin/The Washington Post)

The partial shutdown of the federal government entered its fifth day Wednesday, as President Trump and congressional Democrats remain at an impasse over Trump’s proposed border wall.

The White House has demanded that Congress approve $5 billion in funding for constructing a wall along the U.S. border with Mexico, a request Democrats have rejected as wasteful and ineffective.

About 25 percent of the federal government has been shut down, with approximately 800,000 federal workers nationwide expected to be affected during the holiday season.

Many national parks across the country have also been closed, and the Internal Revenue Service planned to close taxpayer assistance lines, among other operations, weeks ahead of filing season. On Tuesday, Trump said he could not predict when the government would reopen but suggested he would be flexible about the exact nature of additional funding for border security.

“I can tell you it’s not going to be open until we have a wall, a fence, whatever they’d like to call it,” Trump said. “I’ll call it whatever they want. But it’s all the same thing. It’s a barrier from people pouring into our country.”

An aide to House Minority Leader Nancy Pelosi (D-Calif.) said Wednesday morning that there were “no updates” on the status of negotiations.

Mick Mulvaney, acting chief of staff and director of the Office of Management and Budget, has said “it’s very possible” the shutdown will extend into the new year.

Democrats will take control of the House on Jan. 3 after winning the 2018 midterm elections, and are expected to quickly pass a bill that would fund the government without additional wall funding. It’s not clear if the measure would pass the Senate, where Republicans will add to their majority, and Senate Majority Leader Mitch McConnell (R-Ky.) has said any deal will have to be signed off on by the president.

The urgency to complete a deal may be amplified amid a downturn in the stock market, which suffered the worst decline on Christmas Eve in history and has entered bear market territory in some sectors. The Dow Jones industrial average was up 500 points Wednesday as markets recovered from the sharp decline.

Democrats have pointed to an Oval Office meeting earlier this month in which Trump said he would take credit for shutting down the government. Jim Manley, who served as an aide to former Senate majority leader Harry M. Reid (D-Nev.), said Democratic lawmakers feel little pressure to help him out of a crisis they believe he started.

“It took awhile for some Democrats to learn that Trump has no fixed views, and if he says he’ll be for something one day he’ll be against it in 24 hours,” Manley said. “Democrats see a weakened president who has boxed himself in so badly it’s difficult to see how he’ll get himself out of it without caving. … He has no off-ramps to get him out of this predicament.”

But Chris Chmielenski, director of content and activism at NumbersUSA, said Democrats should back up votes they had taken in previous years to beef up border security. NumbersUSA, which advocates restricting immigration, has generated more than 10,000 calls to the White House and members of Congress as part of the shutdown fight.

“Democrats can come out and say they supported billions for fencing, but when push comes to shove, and this is something that will get passed into law, they suddenly back off,” Chmielenski said.