Washington, December 11: President Donald Trump threatened Tuesday to order the military to build a multi-billion dollar barrier along the US-Mexico border if Democrats refuse funding for the controversial project.

Tweeting ahead of a White House meeting with opposition Democratic party leaders, Trump claimed that the wall was needed to prevent "large scale crime and disease" brought by illegal immigrants.

"If the Democrats do not give us the votes to secure our Country, the Military will build the remaining sections of the Wall. They know how important it is!" he tweeted. Sending Troops to Mexican Border is Trump's 'Political Stunt': Former US President Barack Obama.

Opponents say the wall, arguably Trump's main campaign promise in his 2016 election, is not only a waste of money but has been used by the president to whip up xenophobia.

Chuck Schumer, the senior Democrat in the Republican-dominated Senate, and Nancy Pelosi, who is likely to become speaker in the newly Democrat-controlled House in January, were meeting with Trump later Tuesday.

But the president was unlikely to persuade them to agree to USD 5 billion he says is needed to fund heavy construction along the border. The Democrats are willing to agree to far less, with emphasis on border security rather than an actual wall.

Trump has repeatedly threatened to shut down much of the government if Democrats do not back his plan. Swaths of federal funding will expire on December 21, forcing a partial government closing, unless a deal can be reached.

Washington has been paralysed by political gridlock for most of Trump's two years in office and the partisan divide is set to intensify in January when Democrats take over the majority in the lower house of Congress.

The power shift comes as Trump faces ever growing peril from criminal investigations, with talk growing of possible impeachment proceedings against the president.