The billionaire has announced he is dropping out after a disappointing Super Tuesday. Bloomberg has offered his support to Joe Biden's bid as Elizabeth Warren cast doubt on her candidacy.
Mike Bloomberg dropped out of the Democratic party's presidential race on Wednesday.
The billionaire's announcement came after suffering a string of electoral defeats on Super Tuesday, the most notable day on the primary calendar.
Bloomberg is backing fellow Democrat Joe Biden to become the party's nominee to face US President Donald Trump in November's countrywide elections.
The 78-year-old, who joined the contest 101 days ago, tweeted: "Three months ago, I entered the race to defeat Donald Trump. Today, I'm leaving for the same reason. Defeating Trump starts with uniting behind the candidate with the best shot to do it. It's clear that is my friend and a great American, Joe Biden."
The media mogul spent more than $500 million of his own fortune on his short-lived campaign. It is not yet clear whether he will invest any of his fortune in his support of Biden.
Former vice president Biden was grateful for Bloomberg's approval. He said: "I can't thank you enough for your support — and for your tireless work on everything from gun safety reform to climate change. This race is bigger than candidates and bigger than politics. It's about defeating Donald Trump, and with your help, we're gonna do it."
Three down in a week
The race to be the Democratic nominee appears to have just two serious runners left, Biden and Vermont Senator Bernie Sanders, particularly as Elizabeth Warren is "talking to her team to assess the path forward," a campaign aide said.
The presidential candidate saw disappointing results all round on Super Tuesday. Warren did not finish in the top two in any of the 14 states, including the senator's home state of Massachusetts.
President Trump took to Twitter to express that he wasn't surprised Bloomberg didn't last the pace. "Mini Mike Bloomberg just 'quit' the race for President. I could have told him long ago that he didn't have what it takes, and he would have saved himself a billion dollars, the real cost. Now he will pour money into Sleepy Joe's campaign, hoping to save face. It won't work!"
Bloomberg tweeted in response: "See you soon, Donald," along with a video of the famous scene from Star Wars in which Obi-Wan Kenobi is killed by Darth Vader. Social media users were quick to note wryly that this is the moment in the film series when Obi-Wan effectively passes the torch to the next generation of resistance fighters, never to be seen again except as a ghost.
jsi/msh (dpa, AFP, AP, Reuters)