Bloomberg’s decision appears to reflect a recognition of the long odds he would have faced as a moderate newcomer in an unapologetically liberal party, and his own unsentimental calculus about the trade-offs involved in running. After conducting polling and other research, Bloomberg’s advisers concluded he would have a real but narrow path to the nomination — and that it could all but vanish if Joe Biden, the former vice president, entered the race.

“I believe I would defeat Donald Trump in a general election,” Bloomberg wrote, in a Bloomberg News column announcing his decision. “But I am clear-eyed about the difficulty of winning the Democratic nomination in such a crowded field.”

Though Bloomberg is aligned with Democrats on a range of issues like climate change and gun violence, he is also a proudly pro-business centrist in a party that has moved sharply to the left in its rhetoric and policy proposals. And his record on policing as mayor, as well as his generally favorable view of Wall Street, would likely have proved troublesome in a field that is establishing litmus tests on social justice and corporate power.

In his column, Bloomberg, 76, cautioned Democrats not to shift too far to the left.

“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,” he 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.'”

Rather than entering the race himself, Bloomberg intends to plow his political energy and immense personal fortune into other efforts to thwart Trump and his agenda, including an initiative aimed at rapidly accelerating the country’s transition to renewable energy. He also expects to be heavily involved in the 2020 general election, organizing and financing opposition to Trump.

This article originally appeared in The New York Times.