Donald Trump has launched a bizarre attack against Democratic presidential contenders in a series of tweets in which he joked about serving another 14 years in the White House.

"Could you imagine having Sleepy Joe Biden, or @AlfredENeuman99 or a very nervous and skinny version of Pocahontas (1000/24th), as your President, rather than what you have now, so great looking and smart, a true Stable Genius!" Mr Trump wrote.

"Sorry to say that even Social Media would be driven out of business along with, and finally, the Fake News Media!"

The US president included the Twitter handle @AlfredENeuman99 in reference to South Bends mayor Pete Buttigieg, who Mr Trump has claimed looks like Alfred E Neumen, a caricature from US humour magazine Mad. The handle actually belongs to a retired teacher from Illinois.

"Pocahontas" is a racially charged reference to Elizabeth Warren, who has claimed Cherokee ancestry. The inclusion of "1000/24th" appears to be a bungled allusion to the fact a DNA test showed Ms Warren was at best only 1/64th Native American.

Mr Trump started his rant by touting an upcoming social media "summit", which will see a series of right-wing figures attend the White House, in part to discuss an unfounded conspiracy theory social media companies are suppressing conservative voices.

The US leader said the "big subject" for discussion would be "the tremendous dishonesty, bias, discrimination and suppression practiced by certain companies."

He added: "We will not let them get away with it much longer. The Fake News Media will also be there, but for a limited period the Fake News is not as important, or as powerful, as Social Media.

"They have lost tremendous credibility since that day in November, 2016, that I came down the escalator with the person who was to become your future First Lady."

Mr Trump appeared to confuse his dates - the famous footage of the couple descending the escalators at Trump Tower occured in June 2015, just before he gave a speech launching his presidential campaign.

"When I ultimately leave office in six years, or maybe 10 or 14 (just kidding), they will quickly go out of business for lack of credibility, or approval, from the public," Mr Trump continued. "That’s why they will all be Endorsing me at some point, one way or the other."

Mr Trump has repeatedly joked in recent months about serving more than two terms as president.

Twice in June he tweeted a video meme depicting him campaigning for president throughout the remainder of the 21st century.