Michael Bloomberg, the former New York City Mayor who belatedly upended the 2020 Democratic primary by infusing his campaign with half a billion dollars of his personal fortune, announced Wednesday morning that he was exiting the race and throwing his support behind former Vice President Joe Biden.

“Three months ago, I entered the race for President to defeat Donald Trump,” Bloomberg said in a statement. “Today, I am leaving the race for the same reason: to defeat Donald Trump — because it is clear to me that staying in would make achieving that goal more difficult.”

Bloomberg’s announcement and endorsement of the former Vice President came less than 12 hours after Biden’s surprisingly strong performance in the 15 Super Tuesday contests — the races Bloomberg had invested in to propel him to the nomination. While Biden won nine states, netting surprise victories in Massachusetts, Texas and Minnesota and surpassing Sanders in the delegate contest, Bloomberg won just one contest in American Samoa, and won 44 delegates.

It was a tough blow for the media mogul, who, after entering the race in November, had skipped the first four contests in a bet that a strong Super Tuesday victory would give him the necessary momentum to advance in the race.

Addressing his staff and supporters in midtown Manhattan Wednesday afternoon, Bloomberg became emotional as he emphasized the importance of beating Trump in November. “I will not be our party’s nominee. But I won’t walk away from the most important political fight and I hope you won’t walk away either,” he told the crowd.

“I’m a believer in using data to inform decisions. After yesterday’s results, the delegate math has become virtually impossible —and a viable path to the nomination no longer exists,” Bloomberg said in his statement, and indicated he would funnel resources into assisting Biden. “I will work to make him the next President of the United States,” he said.

Biden quickly thanked his former rival for the backing. “I can’t thank you enough for your support—and for your tireless work on everything from gun safety reform to climate change,” Biden wrote in a tweet. “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.”

Bloomberg’s once-long shot bid seemed to be gaining traction in the beginning of this year, after Biden noticeably faltered in Iowa and New Hampshire with fourth and fifth place finishes. Polling showed he was eating into some of Biden’s African-American support, which is crucial in the southern Super Tuesday states.

He had unlimited resources to build on that support, blanketing the airwaves with ad buys, while Biden had just $7 million in cash on hand heading into February, according to reports filed with the Federal Election Commission.

But when Bloomberg appeared on the debate stage for the first time last month, he looked visibly uncomfortable and stumbled under pressure from his competitors who seemed determine to bring him down. He fumbled through a question from Massachusetts Senator Elizabeth Warren about why his company prohibited former employees who had filed harassment complaints from being let out of their non-disclosure agreements, and another regarding his delayed apology for the controversial stop-and-frisk policies he implemented as Mayor that disproportionately targeted African-Americans.

The performance heightened the anxiety of centrist Democrats who had pinned their hopes on Bloomberg, only to see him stumble. He knew he performed poorly, even joking about it in some of his speeches. On Monday, as he delivered remarks at the annual conference for the American Israel Public Affairs committee, he told the audience, “Israel is small, we know, but resilient—and surrounded by adversaries. And if you caught the last couple of presidential debates, you know that I can empathize.”

By that time, his candidacy had already began to flounder. He and Biden, it seemed, had switched places after the former Vice President’s landslide victory in South Carolina. In the span of 24 hours, Biden’s two top competitors, Pete Buttigieg and Amy Klobuchar, suspended their campaigns and endorsed him. Donors who had previously supported other candidates or remained neutral opened their wallets for him. Though Bloomberg was still in the race, Democratic stalwarts had already begun to position the contest as a two-person contest.

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Write to Alana Abramson at Alana.Abramson@time.com.