LAS VEGAS, Nevada — Michael Bloomberg joins fellow US presidential candidates for the first time on the Democratic debate stage on Wednesday and will face incoming fire from rivals unnerved, even angered, by his increasing prominence in the race.

While candidates like front-runner Bernie Sanders have spent months barnstorming early states, seemingly visiting every town in Iowa and New Hampshire in a personal quest for votes, former New York mayor Bloomberg has parachuted late into the Democratic nomination contest.

The uber-wealthy US media tycoon's rise in polling, fueled by his astronomical spending on campaign advertising, has helped him qualify for his first 2020 debate. His performance will be a massive public test.

It also has boosted the chance of one septuagenarian white male New York billionaire going up against another in the form of President Donald Trump in November's election.

The prospect is not sitting well with Bloomberg's five debate rivals, who are likely to hurl searing salvos at him when they take the stage in Las Vegas for a two-hour showdown starting 6:00 pm (0200 GMT Thursday).

"I got news for Mr. Bloomberg," Senator Sanders, the left-wing firebrand who won last week's New Hampshire primary, told voters Sunday in Nevada. "The American people are sick and tired of billionaires buying elections."

Bloomberg has essentially foregone the campaigning in the first four state-wide contests, including Nevada, which votes on Saturday.

Instead he is going all in on so-called Super Tuesday on March 3, when 14 states including heavily populated California and Texas vote on choosing a Democratic nominee.

The ninth Democratic debate's other participants — former vice president Joe Biden, former South Bend, Indiana mayor Pete Buttigieg and Senator Amy Klobuchar, all moderates, and the more progressive senators Sanders and Elizabeth Warren — have castigated Bloomberg for his campaign approach.

On Tuesday, Warren offered a preview of the fireworks, tweeting "it's a shame" that Bloomberg can "buy" his way into the debate while she and others have expended so much campaign trail shoe leather.

"But at least now primary voters curious about how each candidate will take on Donald Trump can get a live demonstration of how we each take on an egomaniac billionaire," Warren added.

Bloomberg, worth $55.5 billion, was the world's ninth wealthiest person in 2019, according to Forbes.

Buttigieg also took aim at the former New York mayor on Tuesday when asked during a CNN town hall if he thought Bloomberg was trying to buy his way in.

"What else do you call it when you dip into your endless reserves of millions and billions and don't go through the process of campaigning in states like Nevada, or Iowa, or New Hampshire?" Buttigieg asked.

"Humbling yourself, going into the diners and the backyards, looking eye to eye to voters?"

On Tuesday, Bloomberg spokesman Timothy O'Brien said Bloomberg would sell the company that he founded and that made him a billionaire, Bloomberg LP, should his presidential campaign be successful.

On the national stage, the 78-year-old is surging. Two separate polls released Tuesday show him leapfrogging rivals to claim second spot in the party nomination race behind Sanders, with Biden third.

Buttigieg, who narrowly won Iowa and finished second in New Hampshire, will seek to show viewers that his strong early performances were no fluke.

For Warren, Klobuchar and Biden, the former front-runner who performed poorly in those two states, the Nevada debate is a critical opportunity for them to convince voters that they belong in the race heading into the stretch.

For Bloomberg, it could be his introduction to millions of voters unfamiliar with his 12-year stint as mayor of America's largest city.

Some of Bloomberg's policies as mayor are facing sharp criticism.

Several rivals have highlighted the stop-and-frisk police operations during Bloomberg's mayorship that disproportionately targeted and affected people of color.

On Saturday, Bloomberg acknowledged that he defended the policy "for too long" because he failed to understand the "unintended pain" it caused minority families.

"I should have acted sooner and faster to stop it," he said. "I didn't, and for that I apologized."

That has not quelled the furor. "Sixty billion dollars can buy you a lot of advertising, but it can't erase your record," Biden told NBC Sunday.

Trump has eagerly sought to sow discord in the Democratic race, often by attacking "Mini Mike" Bloomberg.

On Tuesday, Trump savaged him for spreading money "all over the place" in a bid to get people to support his campaign.

"Mini is illegally buying the Democrat Nomination," Trump boomed.

As front-runner, Sanders is sure to take incoming debate fire, too.

"He's never gotten anything done," Biden said of Sanders.

While Biden helped pass Barack Obama's health care reforms into law, the former vice president added, Sanders has "been talking about... universal health care for 35 years. Nothing's happened." — AFP