Michael R. Bloomberg knows a lot about third parties.

The former New York mayor has been the country’s most prominent political independent since leaving the Republican Party in 2007, and he has long entertained speculation that he would run for president. In 2016, he told interviewers that he was weighing an independent presidential bid while making his distaste for both Hillary Clinton and Donald Trump well known.

But Bloomberg, who is considering another presidential run, is now a Democrat. It’s not that his politics have changed. The business tycoon, a noted proponent of decisions driven by data and analytics, said that he realized that an independent could never succeed in the United States' electoral system.

Bloomberg’s decision to avoid a third-party candidacy in 2020 has drawn into sharp focus that made by another prominent billionaire. Howard Schultz, the former CEO of Starbucks, announced this week that he was exploring a potential presidential bid as an independent.

In a statement released Monday, Bloomberg spoke harshly of third-party candidacies, pointing to the research he’d done on independent candidacies in the past.

His conclusion was clear: “In 2020, the great likelihood is that an independent would just split the anti-Trump vote and end up reelecting the President."

“The data was very clear and consistent,” he said. “Given the strong pull of partisanship and the realities of the electoral college system, there is no way an independent can win. That is truer today than ever before."

Bloomberg’s statements punctuated the sustained criticism that had been directed at Shultz since his announcement.

“That’s a risk I refused to run in 2016 and we can’t afford to run it now," he said. “We must remain united, and we must not allow any candidate to divide or fracture us.”

The concerns have been voiced by a large group commentators who hope to see Trump defeated in 2020.

In an appearance at a Manhattan Barnes and Noble on Monday, Schultz was confronted by a protester who called him egotistical and said he’d help elect Trump, according to BuzzFeed News reporter Alexis Levinson. Schultz was asked by interviewer Andrew Ross Sorkin about Bloomberg’s comments.

“I don’t agree with his conclusion,” he said, according to Levinson.

Schultz said he would refuse to run as a Democrat.

“If I run for president, I’m running as a centrist independent," he said.

Third-party candidacies have been long fixture of the political landscape in the United States though the electoral college virtually ensures a two-party political system. And there have long been concerns about whether they play the role of spoiler in tight elections. In 2000, Ralph Nader earned nearly 100,000 votes in Florida, a state which tipped the balance of the election. Gore lost the state by 537 votes In 1992, when the incumbent George H.W. Bush was defeated by Bill Clinton, Texas billionaire Ross Perot won 19 percent of the popular vote.

Kyle Swenson contributed to this report.

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