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(CNN) —  

Former New York Mayor Michael Bloomberg has decided against running for president in 2020, he announced on Tuesday.

“As I’ve thought about a possible presidential campaign, the choice before me has become clear. Should I devote the next two years to talking about my ideas and record, knowing that I might never win the Democratic nomination? Or should I spend the next two years doubling down on the work that I am already leading and funding, and that I know can produce real and beneficial results for the country, right now? I’ve come to realize that I’m less interested in talking than doing,” he wrote in an opinion piece for Bloomberg.

“And I have concluded that, for now, the best way for me to help our country is by rolling up my sleeves and continuing to get work done.”

Bloomberg publicly speculated about a 2020 bid for months, traveling the country to meet with voters and determine whether a bid was possible.

Bloomberg told reporters during this public speculation that he was seriously considering a bid, to the point that he decided he would self-fund a campaign.

“In terms of running for office, I ran three times. I used only my own money, so I didn’t have to ask anybody what they wanted in return for a contribution,” he told CNN in January. “The public liked that every time they elected me. And, if I ran again, I would do the same thing.”

Shortly after Thanksgiving, Bloomberg’s team – sensing they needed to be ready – ramped up efforts to hire staff and advisers, said Bloomberg’s longtime adviser Kevin Sheekey. He says Bloomberg’s team hired Obama’s 2008 campaign manager, David Plouffe, several days ago. And Mitch Stewart, who was battleground states director for the 2012 Obama for America campaign, and Obama’s 2012 chief analytics officer, Dan Wagner, were also brought on. Both of them will continue to help Bloomberg throughout the election cycle, said Sheekey.

As recently as three weeks ago, Bloomberg was leaning toward a run.

But polls late last week still showed a narrow path to victory, especially if Joe Biden entered the race, said a person with knowledge of the effort. Bloomberg took the weekend to mull his decision and ultimately decided against a run yesterday, said the person.

Rather than an asset, Bloomberg’s wealth could have been considered a knock against the former New York mayor, given that Democrats like Sen. Elizabeth Warren have demanded that candidates swear off super PACs and self funding.

A number of Democratic operatives believed that a Bloomberg campaign would be doomed by the mayor’s positions on policing, ties to Wall Street and the fact that he spent much of his time in politics as a Republican and independent. But Bloomberg also would have brought considerable strengths to a campaign, including his work on climate change and guns and the fact that he has spent millions on Democratic causes for years.

Bloomberg leaned into his moderate persona in the opinion piece, urging Democrats to nominate someone who could beat Trump, not someone from the far left of the party.

“It’s essential that we nominate a Democrat who will be in the strongest position to defeat Donald Trump and bring our country back together,” Bloomberg wrote. “We cannot allow the primary process to drag the party to an extreme that would diminish our chances in the general election and translate into ‘Four More Years.’ “

After leaving the mayor’s office in 2012, Bloomberg continued to be an influential and recognizable figure on the national and international political stage in part because of his leadership on climate change and gun safety.  He elevated his profile even further last year as he toured the country to speak with voters and local leaders.

At many stops, he blasted Trump over his immigration, environmental and economic policies.  Not only did Bloomberg devote considerable time to his anti-Trump agenda, but the billionaire flexed his financial muscle to see it through. He spent more than $100 million in an effort to wrest control of the Congress from the Republicans.

The success of that effort coupled with positive feedback from voters around the country emboldened Bloomberg and his team of advisers, according to a person familiar with the effort.

But still, Bloomberg kept his team and the country guessing about whether he would jump into the presidential race, with a steady stream of news stories feeding speculation. Adding to that, Bloomberg made an overtly political stop in New Hampshire in January, taking questions at popular campaign stops throughout the state.

In announcing that he isn’t running for president on Tuesday, Bloomberg said he would instead be launching a new campaign called “Beyond Carbon,” which he described as a “grassroots effort to begin moving America as quickly as possible away from oil and gas and toward a 100 percent clean energy economy.”

“At the heart of Beyond Carbon is the conviction that, as the science has made clear, every year matters,” he wrote. “The idea of a Green New Deal — first suggested by the columnist Tom Friedman more than a decade ago — stands no chance of passage in the Senate over the next two years. But Mother Nature does not wait on our political calendar, and neither can we.”

What Bloomberg does with his money beyond his series of outside organizations will be a key question for Democrats in 2020, given that his considerable wealth could tip the balance for a number of candidates in a crowded field.

This story has been updated.