Michael Bloomberg called Donald Trump a “carnival barking clown” on Thursday as the former New York mayor returned fire while his chances of becoming the Democratic presidential nominee continue to tick up. The billionaire and late entrant in the race sat out the first two votes in Iowa and New Hampshire but has seen a boost after the leading moderate, former US vice president Joe Biden, stumbled in both states. This week the Trump campaign has escalated their attacks on Mr Bloomberg in a sign that they see his candidacy possibly surging when he is on the ballot in contests next month. On Thursday Mr Trump repeated his “Mini Mike” tweets, taking aim at Mr Bloomberg’s height and repeating a claim denied by his campaign that he requested a stool for the next debate. The president tweeted: “Mini Mike is a 5’4” mass of dead energy who does not want to be on the debate stage with these professional politicians. No boxes please. “He hates Crazy Bernie and will, with enough money, possibly stop him. Bernie’s people will go nuts!” The height was wrong. Mr Bloomberg is actually five foot eight inches. Mr Bloomberg, 77, wrote back on Twitter: “We know many of the same people in NY. Behind your back they laugh at you & call you a carnival barking clown. “They know you inherited a fortune & squandered it with stupid deals and incompetence. I have the record & the resources to defeat you. And I will.” The exchanges captured the Trump campaign’s increasing willingness to call out Mr Bloomberg and the latter’s enthusiasm to go toe-to-toe with the president on social media. Mr Bloomberg had announced early last year that he would not be seeking the Democratic nomination, citing the strong polling performance of Mr Biden. However he reversed that decision in November amid suggestions Mr Biden’s pitch might not be as strong as it appeared, positioning himself to benefit if the front-runner stumbled. Since then Mr Bloomberg has poured hundreds of millions of dollars into an advertising campaign. He will join the race on so-called Super Tuesday, when more than a dozen states vote on March 3. Mr Biden’s fourth- and fifth-place finishes in Iowa and New Hampshire have left his campaign in freefall, while there are doubts about the two strongest performers so far - left-wing senator Bernie Sanders and 38-year-old former South Bend mayor Pete Buttigieg. Mr Bloomberg, a former Republican who created the Bloomberg financial empire, is positioning himself as the moderate candidate who can defeat Mr Trump and win over centrist voters if Mr Biden’s campaign continues to flop. The billionaire has been paying internet stars to produce memes on his behalf, in an apparent attempt to woo younger voters and a reflection of his bid’s vast financial power. One involved what looked like a genuine Mr Bloomberg online profile asking for someone to create a meme for him, before adding: “Please fax it over before the markets close.” Mr Bloomberg has the third most endorsements in the race, behind Mr Biden and Massachusetts senator Elizabeth Warren, according to a tracker run by the political website Five Thirty Eight. Yet his path to victory still looks narrow, with people on the party’s left-wing unlikely to be won over by Mr Bloomberg’s moderate policy platform and immense wealth. Mr Sanders, who won most votes in both Iowa and New Hampshire, has in recent days been warning against billionaires “buying” elections, saying it is tantamount to corruption. Meanwhile the Trump campaign has been releasing videos unearthed from the archives of Mr Bloomberg defending his controversial stop and frisk police policy while New York mayor, questioning his legacy of tackling racial injustice.