At 6 feet 2 inches, President Trump towers over, the diminutive 5-foot-7-inch former three-term mayor of New York City. Mr. Trump has taunted Bloomberg on Twitter, referring to him as "mini" and questioning his chances to become the Democratic nominee in the 2020 election.
"Mini Mike Bloomberg doesn't get on the Democrat Debate Stage because he doesn't want to - he is a terrible debater and speaker. If he did, he would go down in the polls even more (if that is possible!)," Mr. Trump wrote on Twitter Friday.
He wrote a second tweet on Friday referring to Bloomberg's numerous ads against the president airing on TV.
"Mini Mike Bloomberg ads are purposely wrong - A vanity project for him to get into the game. Nobody in many years has done for the USA what I have done for the USA, including the greatest economy in history, rebuilding our military, biggest ever tax & regulation cuts, & 2nd A!" Mr. Trump wrote.
Although Mr. Trump occasionally tweets about Democratic presidential candidates, Bloomberg in particular seems to have nettled the president. Like Mr. Trump, Bloomberg is a billionaire from New York, but his fortune is considerably larger; Bloomberg's net worth is $60 billion, according to Forbes' real time net worth tracker, as of January 17. Forbes pegs Mr. Trump's net worth at just over $3 billion on the same day.
Bloomberg shot back at Mr. Trump on Twitter, saying that the president was "the expert on vanity projects."
Friday was not the first time Mr. Trump has tweeted angrily about Bloomberg. On Monday, he reiterated that "Mini Mike Bloomberg is spending a lot of money on False Advertising."
The tit-for-tat appeared to continue in an escalation of spending over Super Bowl campaign ads. Earlier this month, the Bloomberg campaignto air nationally during the Super Bowl, the highest-watched television event of the year, costing roughly $10 million to be aired once.
The ad was purchased in part to counter what was expected to be a 30-second national spot purchased by the Trump campaign. However, a senior Trump campaign official then confirmed to CBS News that the campaign would be spending $10 million on 60 seconds of airtime during the Super Bowl.
But the enmity between the two existed before the 2020 election, and hit a boiling point after Bloomberg's speech at the 2016 Democratic Convention, when Bloomberg belittled Mr. Trump's fortune.
"Throughout his career, Trump has left behind a well-documented record of bankruptcies, thousands of lawsuits, angry shareholders, and contractors who feel cheated, and disillusioned customers who feel ripped off. Trump says he wants to run the nation like he's run his business. God help us," Bloomberg said in the speech. "I'm a New Yorker, and New Yorkers know a con when we see one!...Truth be told, the richest thing about Donald Trump is his hypocrisy."
Mr. Trump responded in kind on Twitter, although he had not yet formulated the "mini" epithet.
""Little" Michael Bloomberg, who never had the guts to run for president, knows nothing about me. His last term as Mayor was a disaster!" Mr. Trump wrote.
Bloomberg will not be on the ballot in the Iowa caucus or New Hampshire primary, choosing instead to focus on more delegate-rich states that will have their contests in March. Bloomberg is spending millions to bolster this untested strategy, but it's unclear if it will be enough to successfully challenge top-tier candidates like former Vice President Joe Biden and Senator Bernie Sanders.
Regardless of who wins the Democratic nomination, Bloomberg has promised to devote a significant chunk of his considerable wealth to taking down Mr. Trump.
But if he does win the presidency, unlike his predecessor, Bloomberg's Twitter account will go silent. In every stump speech, Bloomberg commits to voters that he will not tweet from the White House.