Democratic Party's electoral calculus is set for a recalibration on Wednesday night when the controversial billionaire Michael Bloomberg steps on to the stage for the first time to debate the other candidates vying for the nomination to challenge US President Donald Trump in the November election.

Propelled by an estimated $300 million-ad blitz, Bloomberg has surged in national polls to become the top center-right candidate claiming the middle ground as former Vice President Joe Biden slumped.

Bloomberg will be the target of the five others in the debate when they are expected to rake up his past anti-minority actions as the mayor of New York and his racists and sexist comments.

This will be the first time he will have to publicly spell out his platform and answer to criticisms having missed the previous eight debates, relying instead on TV commercials to build his image, and avoided the two intra-party state elections so far and the forthcoming two.

Michael Bloomberg
Michael Bloomberg Wikimedia commons

The race between Sanders and Bloomberg

The race for the nomination has now sharpened to a head-to-head confrontation between the left-wing represented by self-proclaimed socialist Senator Bernie Sanders and the moderate by Bloomberg.

The latest poll that qualified him for the debate in Las Vegas, gave him 19 percent support, while Sanders had 31 percent.

Biden, once considered the front-runner, was trailing with 15 percent support.

Three other polls had shown him over the ten percent mark required to qualify for the debate.

However, the first real test of the strength of the candidates will be on March 3 when 14 states, including California, will be holding their intra-party elections known as primaries with secret ballots to select the nominee for the November election.

The party's establishment may find Bloomberg's rise comforting as it has been uneasy with Sanders, fearing that his leftist stance could drive away moderate voters.

Despite his racist and sexist comments and his position as an elitist billionaire, many Democrats have signaled support for him as they say he is the strongest candidate to defeat Trump - which is the only thing that matters to most in the party.

With his deep pockets and a feisty, abrasive demeanor he could match fellow New Yorker Trump's insults and bombast.

A mega-billionaire and mere billionaire race in November?

If Bloomberg, 78, wins the party nomination, the November election will be a contest between a mega-billionaire with assets estimated at about $61 billion, and a mere billionaire, Trump, 73, with assets estimated between $1.5 billion and $3.5 billion.

Both the Democrat front-runners do not have deep organic party connections: Bloomberg is a former Republican and Sanders, a self-described socialist, is officially an independent in the Senate.

Bloomberg made his fortune on Wall Street and is the owner of the news and financial information company that bears his name and provides data terminals to the financial industry while also operating a news service and radio and TV networks.

Bloomberg has been spending his own money for his campaign, unlike the other candidates - and Trump - who have been raising funds from supporters.

Presaging the attacks he will face from the other five candidates, Sander said, "The American people are sick and tired of billionaires buying elections."

To participate in the eight party debates held so far, candidates had to show that they received contributions from a minimum number of supporters - 225,000 for the eighth debate on February 7 - but that requirement has been done away with for Wednesday's debate.

Bloomberg, who was funding his own campaign, was blocked from previous debates by the fund-raising requirement and now the qualification is based on poll performances which he has met.

Trump stoked the rivalries in the Democratic Party with a tweet that its leadership was rigging the race against Sanders -- a charge made by his supporters in 2016 when he challenged Hilary Clinton.

Trump had earlier said that he would rather face Sanders than Bloomberg in November.

While Sanders can turn off moderates, Bloomberg can appeal to a wide range of voters from moderates to right-of-center.

Bloomberg has a controversial past because of his policies towards minorities as mayor and racist and sexist statements he has made.

He has been criticized for these by his rivals and some other party leaders.

But so far he seems to have buried his past partially at least, with his ad blitz that featured clips of former President Barack Obama, an African American, praising him - and overshadowing the fact that Biden was his vice president.

The 'stop and frisk' racism

As mayor, he introduced a "stop and frisk" program under which police randomly stopped and searched non-white youth and courts declared it unconstitutional because of the racial bias.

After ending his third term as mayor, he crudely defended his policy of "throw them against the wall and frisk them" claiming that "95 percent of your murders and murderers" were "male minorities 15 to 25" and "you can just take the description and Xerox it and pass it out to all the cops."

He also defended the illegal policy of financial institutions denying housing loans to non-whites asserting that ending it caused the 2008 financial crisis.

He and his company have faced several lawsuits alleging discrimination against women and denigration of them.

In one of the suits, he is alleged to have asked a woman employee who was pregnant to "kill it," a charge he has denied.

Some of these views could appeal to the extreme right in Trump's base of supporters because Trump, who is accused of being a racist by Democrats, has not made such directly racist statements, at least in recent years.

Bloomberg has apologized for his comments.

Bloomberg, who entered the race late, has followed a strategy that focuses on the states that have a more substantial number of delegates at the party's national convention which will anoint the Democrat presidential candidate.

That left the other candidates - who numbered about 20 at the start of the campaign last year - and have been whittled down to five now - spent millions of dollars fighting each other in the two early party elections that have taken place and two later this month and tearing up each other's images.

Along with his ad campaign, he has built a campaign network that pays staff top salaries.