Would-be US president Donald Trump has hit back after he was the butt of a series of jokes – including jibes from Joe Biden – at the White House Correspondents Dinner.

Keen political watchers might have expected quite the spray after Biden called his presidential rival a “six-year-old” and comedian Colin Jost let rip.

But, at least by his standards, Trump’s response was actually quite tame.

“The White House Correspondents’ Dinner was really bad,” he wrote on his Truth Social platform.

“Colin Jost BOMBED, and Crooked Joe was an absolute disaster! Doesn’t get much worse than this!”

At the century-old annual event, often referred to as Washington’s “nerd prom”, hundreds of journalists, politicians and celebrities rub elbows in a massive banquet hall on Saturday night (US time).

Donald Trump responded to the jokes on Truth Social.

Biden admits age is an issue

Biden used the stage at the dinner to chide his Republican rival for immaturity, poke fun at his own advanced age and take on the Washington press corps.

“Yes, age is an issue [in the US presidential contest],” Biden said.

“I’m a grown man, running against a six-year-old.”

It wasn’t the only time the 81-year-old presidential incumbent compared himself to the 77-year-old Trump, saying it was the only thing they have in common.

“My vice-president actually endorses me,” Biden said.

Famously, Trump’s former vice-president Mike Pence has declined to back his one-time boss at this year’s election.

More seriously, Biden also implored the media not to take sides before the November election and instead “rise up to the seriousness of the moment”.

“Move past the horse race numbers and the gotcha moments and the distractions, the sideshows that have come to dominate and sensationalise our politics, and focus on what’s actually at stake,” he said.

SNL host jokes Jimmy Carter could win

Saturday’s gala dinner was hosted by Jost, who is a Saturday Night Live cast member and Scarlett Johansson’s husband.

In his opening monologue, Jost joked that the last time he was at the White House, he left behind his cocaine and then Biden was able to “put it to good use for a State of the Union”.

“I’m kidding, of course – the President doesn’t call it cocaine, he calls it high-speed rail,” he said.

“By the way, can you blame the guy for turning to cocaine? He must be exhausted orchestrating four separate trials against his rival, rigging the Super Bowl and gearing up to steal a second election.”

Colin Jost with Biden at Saturday’s dinner.

Jost said Trump had two attacks for Biden: That he is a “senile old man” and a “criminal mastermind”.

“I think you got to pick one. Personally, I don’t know any criminal masterminds who biked to get ice-cream,” Jost said.

“Also, it’s not like Trump himself is young and sharp. I’m not saying both candidates are old, but you know Jimmy Carter is out there thinking ‘I could maybe win this thing’.”

Jost also made no secret of his support for Biden.

“My grandfather voted for you in the last election he ever voted in. The reason he voted for you is because you’re a decent man. I thank you for your decency,” he said.

Protesters gather outside

Outside the Washington Hilton, hundreds of protesters encouraged journalists to boycott the event and shouted down Biden administration officials as they entered.

Biden avoided the protests by arriving through a back entrance, where he was greeted by smaller groups of protesters calling for a ceasefire in Gaza.

The growing movement against the war in Gaza has dogged Biden this year, including at a $US250 ($380)-per-ticket March fundraiser at New York’s Radio City Music Hall that was disrupted by protesters.

Recently, that movement has expanded to college campuses in the US, signifying a growing revolt inside the Democratic base that Biden needs to defeat Trump, who is the Republican frontrunner.