'That's the end of that race!': Trump knocks Democrats over healthcare for immigrants

US President Donald Trump, travelling in Asia for the G20 summit, knocked 10 Democratic presidential hopefuls from afar on Thursday for pledging to cover healthcare for immigrants who live in the United States after coming to the country illegally.

During a televised debate in Miami, a moderator asked the presidential candidates, including former Vice President Joe Biden, Senator Kamala Harris of California and South Bend, Indiana, Mayor Pete Buttigieg, if their potential administrations would support covering healthcare for illegal immigrants.

All 10 candidates on the stage raised their hands in the affirmative.

Trump, who has made cracking down on illegal immigration a signature policy of his presidency, pounced via Twitter.

"All Democrats just raised their hands for giving millions of illegal aliens unlimited healthcare. How about taking care of American Citizens first!? That’s the end of that race!" the Republican tweeted.

Trump has promised to build a wall along the US border with Mexico and has declared a national emergency over the number of people crossing into the United States from the south.

The president is in Osaka meeting with world leaders at the Group of 20 summit, but as is customary for him when he travels abroad, he was focused at least in part on goings-on back home.

During a meeting with German Chancellor Angela Merkel, Trump could not help mentioning the Democratic debate.

“You know they have a debate going on,” he said to Merkel. “They had the first debate last night. I don’t know if you saw. It wasn’t very exciting, I can tell you that."

Trump said he looked forward to spending time with Merkel rather than watching the show. The German leader, who worked closely with Republican President George W. Bush and Democratic President Barack Obama during her tenure, kept a straight face.

Thursday was the second night of two debates among 20 candidates who are running for the Democratic presidential nomination to take on Trump in the November 2020 election.

Trump's campaign said both nights would prove to be a boost for the White House incumbent.

“The cast of characters may have changed, but the second night’s script was eerily like the first: a two-hour-long infomercial for President Donald J. Trump's re-election campaign," spokeswoman Kayleigh McEnany said in a statement. "All of the Democrats tripped over each other in a race to see who could stand out as the most leftist candidate, threatening government control of every aspect of people’s lives."

Trump campaign manager Brad Parscale wrote on Twitter that the Democrats were offering everything from free college to free healthcare, houses, cars, boats, aeroplanes and ice cream.

"Nobody has to work! Everyone just gets everything for FREE! Amazing!" he tweeted.

Trump is fond of making fun of the Democratic candidates, assigning pejorative nicknames in the same way that he did to his Republican and Democratic opponents in 2016. On Thursday, the Republican National Committee, while refraining from nicknames, said the Democratic field was one of the extremists.

"Their policies are extreme and out of touch with the realities facing everyday Americans," RNC Chairwoman Ronna McDaniel said in a statement.