Washington: With the US government shutdown entering its third day, President Donald Trump took to Twitter and lamented how he was "all alone" in the White House and aired his many grievances.

"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.

"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. Crazy!" the President said on Monday.

With Congress out of town and the debate over Trump's demand for a $5 billion US-Mexico border wall at an impasse, the President sat holed up, tweeting no less than 10 times by early Monday afternoon to lash out at opponents and reject responsibility for a plummeting stock market.

The Democrats, and even some Republicans, have already made it clear they would not vote for the border wall.

In retaliation, Trump refused to sign a broader spending bill, triggering the stand-off that has left swathes of the US government temporarily without funding.

With funding for roughly a quarter of the US government, including appropriations for the Departments of Homeland Security and Justice expiring on December 22 midnight, a partial shutdown of the federal administration began on Saturday.

The departments of Transportation, Agriculture, State, Housing and Urban Development were on shutdown and federal national parks and forests were also closed.

Outside the White House, Washington's National Christmas Tree became a forlorn symbol of the dysfunction gripping Trump's presidency two years after his surprise election.

The National Park Service tweeted that the tree would remain unlit and closed to the public "until further notice", with checks being made for damage following an attempt by an intruder on Friday to climb the tree.

Hundreds of thousands of federal employees have to work unpaid or have been put on temporary leave.

Twitter users posted memes and trolled the President as Christmas celebrations kicked off across the globe.