Yet his decision to enter the race—after first announcing he wouldn’t—has garnered more skepticism than excitement. Even as the climate crisis is expected to play a major role in the presidential contest for arguably the first time, climate activists questioned the theory of his candidacy.

There’s already a pair of top-tier populists in Sens. Bernie Sanders (I-Vt.) and Elizabeth Warren (D-Mass.). There’s already Washington Gov. Jay Inslee (D), an experienced politician running on the most comprehensive climate policy platform ever put forward. Venture capitalist Andrew Yang already plays the part of the wealthy businessman with provocative ideas. Older, straight, white men make up 13 of the 24 candidates.

“I really don’t get it, man,” said a top climate policy researcher in California who requested anonymity because Steyer “has a lot of money” that is used to support climate work around the country.

In 2013, Steyer founded NextGen America as an environmental advocacy group and political action committee, though the organization broadened its scope in recent years to focus on turning out young voters for progressive causes. The 62-year-old donates generously to Democratic candidates. He poured millions into a high-profile campaign to impeach President Donald Trump.

The Steyer campaign did not respond to an interview request Thursday.

“I wish he weren’t doing it,” said a prominent activist, who also asked for anonymity for fear of souring a relationship with one of the movement’s top funders. “There was always that question in the back of everybody’s minds of whether he’s driven by ego and whether he’s all out for him, or whether he’s trying to build a movement. This answers the question clearly.”

Bill McKibben, the writer and 350.org founder who wooed Steyer to the climate movement nearly a decade ago, didn’t respond to emails and Twitter messages requesting comment. Other 350.org officials declined to comment on Steyer’s candidacy. So did Democratic strategist Henry Waxman, the former California congressman who led the charge on the last major climate bill.

“It’s hard to make the case for a billionaire running for president in this day and age,” said Julian Brave NoiseCat, the Green New Deal strategist at the left-leaning think tank Data for Progress (and a past HuffPost contributor). “Especially this late in the game, and especially when we were all under the impression he was not running.”

Steyer said during a January trip to Iowa that he wouldn’t run for president, instead maintaining his focus on his impeachment effort. In private, he feted Warren’s rhetoric on economic inequality and was excited about Inslee’s climate-centered campaign. But, according to The Atlantic, Steyer grew frustrated with Inslee’s failure to take off as the governor’s polling stayed stuck at 1 percent.