WASHINGTON (AP) -- Michael Bloomberg, the billionaire former New York City mayor, announced Tuesday that he will not join the crowded field of Democrats running for president in 2020.
Instead, Bloomberg said he planned to focus his energy and considerable resources on outside efforts aimed at defeating President Donald Trump, as well as on combating climate change and addressing gun violence.
Bloomberg spent months weighing a White House run, traveling to early voting states and building a team of experienced political advisers. But aides said internal polling suggested Bloomberg's path to the Democratic nomination was narrow, particularly if Vice President Joe Biden -- who shares some of Bloomberg's moderate positions -- decides to run.
In an editorial for Bloomberg News -- the media company Bloomberg owns -- he said he was "clear-eyed about the difficulty of winning the Democratic nomination in such a crowded field."
Bloomberg has flirted with a presidential run before, but as an independent. He registered as a Democrat last fall and began pitching himself to primary voters as a political centrist. But as an older white man with strong ties to Wall Street, he may have struggled to win over the Democratic Party's energized liberal base that's increasingly embracing diversity.
He encouraged Democrats on Tuesday to unify behind a nominee who could beat Trump, a not-so-subtle dig against candidates pushing the party to embrace liberal priorities such as "Medicare-for-all."
"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.'"
Bloomberg aides said Biden's likely White House run was a factor in the mayor's decision. The team's internal polling showed that there is an opportunity for a moderate, like Bloomberg or Biden, to win the Democratic primary, but there wasn't room for both.
Biden may not announce his final decision until April. But Bloomberg concluded that was too long to wait to make his own decision, and he informed advisers on Monday that he would not be running for the White House.
Bloomberg does plan to keep his political network together as he considers how to play a role in the 2020 election from the outside. He's consulting several top advisers to former President Barack Obama, including David Plouffe, the architect of Obama's 2008 campaign, data guru Dan Wagner and Mitch Stewart, Obama's battlefield-states director.
While details of the effort are still being discussed, aides said the goal is to build a robust and well-funded effort to target Trump even as Democrats are still locked in a competitive primary that could stretch deep into 2020.
"Making sure Trump doesn't have the field to himself is really important," Plouffe said.
It's unclear how much money Bloomberg is willing to plunge into the effort. He invested more than $100 million to help Democrats in the 2018 midterm election and his team has discussed going much further in 2020.
Washington Gov. Jay Inslee is now the only candidate in the 2020 race putting climate change front and center in his campaign, but he declined to speculate Tuesday at a campaign stop in Iowa on whether Bloomberg's departure from the field would boost his bid.
"Whether we were in the same race or he is doing work as a private citizen, I know we will be allied in some sense eventually, one way or another, because he has just been so visionary on this for such a long period of time," Inslee said. "So I look forward to working with him one way or another."