Rising White House hopeful Michael Bloomberg has been taking heavy fire from fellow Democratic rivals hours ahead of a live TV debate.
Wednesday night’s forum in Nevada is the first major test for Mr Bloomberg after a late entry to the race.
He is under attack from rivals Joe Biden and Bernie Sanders on his policy platform and personal health.
The billionaire is also likely to have his controversial past remarks on race and gender thrown back in his face.
Eight hopefuls remain in the race to be the Democratic White House candidate. The winner will be chosen at the party convention in July before facing President Donald Trump, a Republican, in November’s election.
Mr Bloomberg is not competing in the first four Democratic leadership ballots this year, instead banking on a strong showing in the so-called Super Tuesday contest on 3 March, when 14 states will vote.
The former New York City Mayor has so far made up for his belated entry with a spending blitz, pouring more than $400m (£310) already on national ads.
In order to take part in the Nevada debate, he had to score above double digits in four national polls recognised by the Democratic party.
The attacks from his Democratic rivals suggest it will be a tough night for the world’s ninth richest man.
Sanders v Bloomberg
Mr Bloomberg and Senator Bernie Sanders have squabbled repeatedly, attacks that have intensified in recent days.
Mr Sanders took a direct swipe at the billionaire on Tuesday night, railing against Mr Bloomberg and “a system that allows billionaires to buy elections”.
“Here is the message: Anyone here worth $60bn, you can run for president, and you can buy the airwaves. My friends, that is called oligarchy, not democracy,” Mr Sanders said.
Mr Bloomberg hit back at the self-described democratic socialist, comparing Mr Sanders’ tactics to President Trump’s.
The two campaigns have also sparred over their respective candidate’s health records.
Defending Mr Sanders’ decision not to release additional medical records related to his heart attack in October, Sanders press secretary Briahna Joy Gray claimed that Mr Bloomberg had suffered heart attacks of his own.
The businessman’s campaign manager fired back, calling the statement from Sanders’ team an “absolute lie” and “completely false”.
If either man – both 78-years-old – were to win the presidency, he would become the oldest occupant of the White House.
Ms Gray later said on Twitter that she “misspoke”.
Biden v Bloomberg
Former Vice-President Joe Biden has also taken shots at the New York tycoon, focusing his attacks on Mr Bloomberg’s campaign ads touting his relationship with former President Barack Obama and his past party affiliation.
“The truth is he’s basically been a Republican his whole life,” Mr Biden said on Wednesday. “The fact of the matter is he didn’t endorse Barack or me when we ran. This is a guy… using Barack’s pictures like, you know, they’re good buddies.
“I’m going to talk about his record.”
Mr Biden’s suggestion that Mr Bloomberg’s relationship with Mr Obama was more tenuous than the ads suggest has been echoed by others in the Obama administration.
“It’s jarring to see all these Bloomberg ads that suggest Obama has endorsed him, especially considering how… perfunctory his endorsement of Obama was back in 2012,” said former Obama spokesman Tommy Vietor on Twitter.