WASHINGTON – As the partial government shutdown entered a third day on Monday, President Donald Trump sought to cajole Democrats into a budget agreement that remained elusive, at one point lamenting he was "all alone" waiting for a deal.

With little progress on his demand for a $5 billion border wall and most lawmakers away for Christmas, the president repeatedly took to Twitter to argue for the border funding. He also scheduled a meeting Monday afternoon with top Homeland Security officials.

"I am all alone (poor me) in the White House waiting for the Democrats to come back and make a deal on desperately needed Border Security," the president posted on Twitter. "At some point the Democrats not wanting to make a deal will cost our Country more money than the Border Wall we are all talking about."

Markets slumped on a shortened Christmas Eve trading day as investors grappled with the shutdown and the lack of progress toward a solution. Treasury Secretary Steven Mnuchin's effort to calm investors appeared to backfire after he made an unprompted statement over the weekend that U.S. banks are healthy – an assurance that seemed only to inject uncertainty on Wall Street.

The Dow Jones Industrial Average fell 653 points, or 2.91 percent, to end at 21,792 on a trading day that was shortened by the holiday. Reports that Trump had considered firing Federal Reserve Chairman Jerome Powell added to the market jitters.

The top Democratic leaders in Congress issued a joint statement accusing Trump of "plunging the country into chaos" on Christmas Eve.

"The stock market is tanking and the president is waging a personal war on the Federal Reserve – after he just fired the Secretary of Defense," Senate Democratic Leader Chuck Schumer and House Speaker-nominee Nancy Pelosi said in statement after Trump posted his 10th tweet of the day. “Instead of bringing certainty into people’s lives, he’s continuing the Trump Shutdown just to please right-wing radio and TV hosts."

Trump had a relatively light public schedule on Monday but tweeted about several contentious issues, including the border security fight. He was scheduled to meet with Department of Homeland Security Secretary Kirstjen Nielsen on Monday afternoon to discuss border issues, the White House said.

“Nothing new on the shutdown," the president told reporters after he and Melania Trump took part in a tradition in which presidents call children across the country on Christmas Eve. "We need more border security.”

Experts note a wall would not likely have a major impact on illicit drugs, which are frequently smuggled into the U.S. through legal ports of entry.

Acting White House Chief of Staff Mick Mulvaney said Sunday the White House had made a new offer to Democrats for a funding bill that would spend more than the $1.3 billion for border security that Democrats already support but less than the $5 billion for border-wall construction that Trump has called for publicly.

On Capitol Hill, both the House and Senate held pro forma sessions that lasted only a matter of minutes, with no votes or official business. Because the Senate won't meet again until at least Thursday, Mulvaney said the shutdown could continue into the new Congress, which begins Jan. 3. Democrats, who will take control of the House that same day, will have additional leverage to negotiate with Trump in the new year.

"I don't think things are going to move very quickly," Mulvaney told "Fox News Sunday."

The White House provided what he called a counteroffer Saturday to Schumer, D-N.Y. "The ball right now is in their corner," Mulvaney said.

In their joint statement, Schumer and Pelosi said the White House has sent conflicting signals about the president's demands.

"Different people from the same White House are saying different things about what the president would accept or not accept to end his Trump Shutdown, making it impossible to know where they stand at any given moment," the two Democrats said. "The president wanted the shutdown, but he seems not to know how to get himself out of it."

The Washington Post reported that the White House's latest request was $2.1 billion for border security and another $400 million for other Trump immigration enforcement efforts. A Democratic congressional aide, who was not authorized to discuss the negotiations publicly, confirmed those figures.

Democratic lawmakers have blasted Trump's proposed wall as expensive, ineffective and immoral.

Many lawmakers have left Washington to spend the holidays with their families. But spending talks continued amid a weekend of football and basketball games, with little outcry over the shutdown. But Mulvaney said because Monday and Tuesday are federal holidays, "Wednesday is really the first day that this kicks in."

To keep Grand Canyon National Park open for a week, Arizona Gov. Doug Ducey signed an executive order to provide $64,000 that will keep the park and essential functions such as trash collection, restrooms and ranger services. The government's Santa tracker was online Christmas Eve, because the agency that runs it relies heavily on volunteers to carry out the tradition.

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Some Republicans have expressed frustration with the White House's strategy. Sen. Bob Corker, R-Tenn., the outgoing chairman of the Foreign Relations Committee and a frequent Trump critic, told CNN that the shutdown was “unnecessary” and “juvenile” because both parties want to work on immigration issues.

Corker noted that Democrats and Republicans supported legislation to provide $25 billion for border security while also dealing with young immigrants who arrived with parents who entered the country illegally. The legislation wasn't ultimately approved. But in contrast, Corker said the shutdown fight is over much less.

"This is a made-up fight," Corker said. "This is something that is unnecessary. It's a spectacle. And, candidly, it's juvenile."

The shutdown takes place during an especially chaotic time in the Trump administration, including the resignation Thursday of Defense Secretary Jim Mattis after Trump announced withdrawal of U.S. troops from Syria, a plunging stock market and Trump attacks on Federal Reserve Chairman Jerome Powell.

Schumer had blamed the shutdown on Trump’s “two-week temper tantrum” over border-wall funding and said the Senate has no interest “in swindling American taxpayers for an unnecessary, ineffective and wasteful policy.”

“President Trump, if you want to open the government, you must abandon the wall, plain and simple,” he said.

Senate Majority Leader Mitch McConnell, R-Ky., said senators would be told when a vote was scheduled and that "negotiations will continue" in the meantime. The Senate next plans to meet Thursday for debate. The House has instructed lawmakers no votes are expected until at least Thursday.

At the White House on Saturday, Trump, who postponed his end-of-the-year trip to Florida, huddled with his advisers and with a small group of GOP lawmakers to discuss border security but did not include Democrats in the meeting. Among the Republicans who were invited were members of the hard-line conservative House Freedom Caucus, which has urged Trump not to abandon the fight for border wall funding.

“This is not about the wall for Democrats. It’s not even about immigration for Democrats,” tweeted Rep. Matt Gaetz, R-Fla. “This is about denying (Trump) a win on a signature agenda item that he promised the American people.”

The latest shutdown – the second one this year and the third of Trump’s presidency – was triggered just after midnight Friday when the budget standoff caused funding to lapse for nine federal departments and several smaller agencies. A quarter of the government shut down, and some 800,000 government employees were forced to go on furlough or work without pay.

Agencies impacted include the FBI, the Bureau of Prisons, Customs and Border Patrol and the IRS, as well as national parks and forests. In all, the nine departments affected are Agriculture, Commerce, Justice, Homeland Security, Interior, State, Transportation, Treasury and Housing and Urban Development.

The White House said federal employees in those departments would be paid for days worked before the shutdown began. The pay period ended on Saturday, and those checks will go out on Dec. 28. Employees deemed “essential” and forced to work during the shutdown will be paid once federal funds start flowing again, the Trump administration said, although that would require congressional action.

Meanwhile, behind-the-scenes negotiations continue – primarily at the staff level – in an attempt to break the funding impasse and end the shutdown. The House has passed a bill that includes $5.7 billion in funding for border security, including a wall. But the proposal is stalled in the Senate and cannot pass without the support of Democrats.

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