WASHINGTON — President Trump and Michael R. Bloomberg, the former mayor of New York City, have been slinging insults at each other for weeks, but their Twitter war reached a new level on Thursday.
Mr. Trump called his rival a “mass of dead energy.” Mr. Bloomberg described the president as “a carnival barking clown.”
The two wealthy New Yorkers are longtime rivals. But now that Mr. Bloomberg is vying to become the Democratic presidential nominee to face Mr. Trump in November, their relationship has turned highly combative.
Mr. Trump started the most recent fight early Thursday, calling Mr. Bloomberg, whom he calls “Mini Mike,” a “LOSER” in one tweet and a “mass of dead energy” in another.
Mr. Bloomberg responded with a warning that showed a familiarity with the president’s past that other Democratic candidates cannot claim. And in the process, he touched on some of the president’s more sensitive subjects: being laughed at behind his back and being called a bad businessman.
Since Mr. Bloomberg announced in November that he was running for the Democratic nomination, he has placed most of his focus on attacking Mr. Trump instead of on his other primary rivals.
And with no spending restraints, Mr. Bloomberg has shown that he can hit the president from different directions with a battery of attacks in television ads airing in key states across the country.
While other Democratic candidates have argued with one another on the debate stages about who is best suited to run against Mr. Trump, Mr. Bloomberg has focused on criticizing Mr. Trump on health care and spent more than $88 million in television ads on the subject since announcing his candidacy.
Mr. Trump has focused many of his insults on Mr. Bloomberg’s height, which is comparatively much shorter that Mr. Trump’s. But the sparring has started to look like they are already running against each other.
Earlier this week, Mr. Trump turned to Mr. Bloomberg’s record as mayor and called him a “TOTAL RACIST” in a Twitter post in which he shared with his 72.4 million Twitter followers an audio recording of Mr. Bloomberg defending a city policy that targeted minorities while he was mayor.
Mr. Trump’s tweet was later deleted, and Mr. Bloomberg reframed it as the latest example of the president’s “endless efforts to divide Americans.” But before that, Mr. Bloomberg had tweeted his defense of the stop-and-frisk policy that Mr. Trump had referenced.
The Trump campaign pointed to cable news coverage about Mr. Bloomberg’s record on race as a “hugely effective” way to redirect the narrative.
Mr. Bloomberg responded that the president had attacked him because of his “fear over the growing strength of my campaign.”
He added, “Make no mistake, Mr. President: I am not afraid of you, and I will not let you bully me or anyone else in America.”
The next day, Mr. Bloomberg tweeted, “Donald Trump is the world’s biggest schoolyard bully — with no respect for civility or decency, or facts or honesty.”