In order to prevent Donald Trump from securing a second term, former New York City mayor Michael Bloomberg, 77, was considering a 2020 presidential run. The Bloomberg L.P. CEO even took steps in preparation for a potential White House bid, including re-registering as a Democrat and preparing a war chest of money to spend during the election season.

However, Bloomberg announced on Tuesday through on op-ed piece posted on his news organization that he will not enter the 2020 race. Although the former mayor believes he would defeat Trump in the general election, he admitted that the crowded nature of the Democratic primaries does not guarantee he would secure his party’s nomination.

“I know we can do better as a country,” Bloomberg writes. “And I believe I would defeat Donald Trump in a general election. But I am clear-eyed about the difficulty of winning the Democratic nomination in such a crowded field.” Had he entered the race, Bloomberg would have positioned himself as a centrist alternative to the more progressive Democrats.

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However, Bloomberg does not plan to sit idle on the sidelines. Beyond Carbon, his campaign to assist in transitioning the country toward clean energy, will become a focal point in his work. “At the heart of Beyond Carbon is the conviction that, as the science has made clear, every year matters. 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.”

Moreover, Bloomberg will utilize his resources to help improve gun safety, public education, and reduce college costs and opioid addiction. “On these and other issues, Washington is unlikely to take effective action over the next two years. Progress depends entirely on the rest of us.” The billionaire philanthropist also plans to assist the Democratic party by “supporting candidates who can provide the leadership we need.”

Bloomberg closes his piece by reiterating his mission: to help the United States as best he can and as quickly as he can. “I hope those who have urged me to run, and to stand up for the values and principles that they hold dear, will understand that my decision was guided by one question: How can I best serve the country? While there would be no higher honor than serving as president, my highest obligation as a citizen is to help the country the best way I can, right now.”