Billionaire Michael Bloomberg will make his first appearance in a Democratic president debate on Wednesday amidst accusations from rivals candidates that he has used his vast personal wealth to “buy” his way into the race.

Bloomberg has spent upwards of $300 million on ads and has run an unorthodox campaign in which he skipped the first four states to hold caucuses and primaries, including Iowa and New Hampshire. He is also not on ballot for the Nevada caucuses that take place next, followed by primaries in South Carolina.

Bloomberg has not been on a debate stage yet, or faced a primary election, but has been creeping up the polls quietly with ads on TV and internet. He has projected himself as someone who can, and will beat, President Donald Trump. And his rise has put him in the cross-hairs of his rivals, and the president.

Others on the stage with him on Wednesday will be Senator Bernie Sanders, who is currently leading the pack with a tie in Iowa and a narrow win in New Hampshire. Former Vice-President Joe Biden, who is struggling to stay in the race, Mayor Pete Buttigieg and Senators Elizabeth Warren and Amy Klobuchar are the other four.

And the president, who has kept an eye on the Democratic race, has been attacking Bloomberg, a fellow New Yorker, with increasing frequency. He has called Bloomberg “Mini Mike” for his height and a “loser”. To which, Bloomberg has said that the only height that matters is the one above the shoulder and has called the president a “carnival barking clown”.