Donald Trump has defended construction of a wall along the US-Mexico border in a bizarre series of tweets in which he compared it to "the wheel" and boasted he understood technology "better than anyone".
"The Democrats are trying to belittle the concept of a Wall, calling it old fashioned," Mr Trump wrote. "The fact is there is nothing else’s (sic) that will work, and that has been true for thousands of years. It’s like the wheel, there is nothing better.
"I know tech better than anyone, & technology on a Border is only effective in conjunction with a Wall. Properly designed and built Walls work, and the Democrats are lying when they say they don’t.
"In Israel the Wall is 99.9% successful. Will not be any different on our Southern Border! Hundreds of $Billions saved!"
Mr Trump's tirade came after House Republicans voted on Thursday evening to allocate more than £5bn towards his proposed border wall as part of a revised spending package to keep the government running over the festive season.
The Senate is being called back to session to consider the bill, but it is almost certain to fail after senators passed their own bipartisan package earlier in the week that kept border security spending at existing levels of $1.3bn.
"The Democrats, whose votes we need in the Senate, will probably vote against Border Security and the Wall even though they know it is DESPERATELY NEEDED," Mr Trump continued on Twitter.
"If the Dems vote no, there will be a shutdown that will last for a very long time. People don’t want Open Borders and Crime!"
The US president later said, "Shutdown today if Democrats do not vote for Border Security!," though any shutdown will come into effect on Saturday.
"Even President Ronald Reagan tried for 8 years to build a Border Wall, or Fence, and was unable to do so," Mr Trump added, without providing evidence.
In a presidential debate in 1980, Ronald Reagan in fact pushed back against the idea of a border structure.
Mr Trump's attempt to blame Democrats for the impending shutdown came just a week after the president said he would be "proud" to shut down the government, which Republicans now control, in the name of border security.
"I will take the mantle. I will be the one to shut it down," he said in a meeting with Democratic leaders Nancy Pelosi and Chuck Schumer.
Mr Trump later implored Mitch McConnell, the senate majority leader, to use the so-called "nuclear option", in which senate rules would be changed so only a simple majority would be required to pass his preferred spending bill.
Currently it takes 60 senators to pass such a bill.
The White House said Mr Trump would not travel to Florida on Friday as planned for the Christmas holiday if the government was shutting down.
More than 800,000 federal workers will be facing a leave of absence or forced to work without pay if a resolution is not reached before funding expires at midnight tonight.
"The president's been clear from the beginning, he wants something that gives border security and he's not going to sign something that doesn't have that," White House press secretary Sarah Huckabee Sanders told reporters.
At issue is funding for nine of 15 Cabinet-level departments and dozens of agencies, including the departments of Homeland Security, Transportation, Interior, Agriculture, State and Justice, as well as national parks and forests.
Many agencies, including the Pentagon and the departments of Veterans Affairs and Health and Human Services, are funded for the year and would continue to operate as usual.
Additional reporting by agencies
Correction: This article initially stated incorrectly a shutdown would begin Monday
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