Billionaire Climate Activist Tom Steyer Weighs 2016 California Senate Run

With Sen. Barbara Boxer retiring, the green spending machine mulls joining a crowded, competitive race to replace her.

Billionaire climate-change activist Tom Steyer might jump into the race to replace retiring Democratic Sen. Barbara Boxer of California in 2016.

"My sense is that he will take a look at it and consider it over the next few days or so," said a source close to the former hedge-fund manager.

The source close to Steyer said the 57-year-old has "developed a lot of friends and relationships" through his work on ballot initiatives, electoral contests, and philanthropy. Steyer's fortune would also come in handy in what promises to be an expensive race.

Other possible Democratic contenders to replace Boxer—who announced Thursday that she won't seek a fifth term—include former Los Angeles Mayor Antonio Villaraigosa, state Attorney General Kamala Harris, and Lt. Gov. Gavin Newsom.

Steyer spent tens of millions of dollars in the 2014 midterm elections trying to elect candidates for the Senate and governors' mansions that favored strong action on climate change. He came away with very mixed results.

Steyer has other options if he decides to seek political office. He's seen as a potential candidate for governor in California in 2018, when incumbent Democrat Jerry Brown's final term will end.

Still, the source noted that Steyer, who has also poured resources into trying to defeat the Keystone XL pipeline, is hardly certain to become a candidate for anything. "He does not get up every morning and plot how to pursue office X or office Y," the source said.

National Journal has more here on the race to replace Boxer.