DEMOCRATS have often feared big money in American politics, perhaps because most of it doesn’t go their way. When the Supreme Court struck down the caps on aggregate campaign donations last week, Republicans, broadly speaking, cheered and Democrats jeered. In the 2012 election cycle, four of the five biggest donors to superPACs—independent groups that raise money, often from the extremely rich, and spend it on outlandish political advertising—were Republicans.

Tom Steyer, a San Francisco-based billionaire who worries about climate change, is doing his best to help his fellow Democrats get over their qualms. Perhaps best known for his opposition to the proposed Keystone XL oil pipeline, Mr Steyer, a former hedge-fund investor, was the biggest superPAC spender last year, dropping $11.1m into his two groups. This year he looks likely to repeat that feat, hinting that he will invest at least $50m in one of them, the NextGen Climate Action Committee (NGCA), and that he will be seeking the same amount from other donors. The money will be spent to help elect politicians who share Mr Steyer’s environmental views, or kick out those who do not.

In November’s mid-term elections, all 435 seats in the House of Representatives and 36 in the Senate will be up for grabs. So will 36 governorships and countless state legislative seats. For NGCA to spend on any given race, says Mr Steyer, three conditions must apply. First, the leading candidates must have differing views on climate change (so Democratic fans of Keystone should be safe; their Republican opponents probably agree with them). Second, “something substantive” must have a chance of happening if the NGCA-backed candidate wins. Third, the race should have the potential to affect the national climate debate.

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At present, though, the focus is political. Many of the elections that have attracted the attention of Mr Steyer’s team this year are in states likely to matter in the 2016 presidential election, including Iowa, Florida and New Hampshire. That is no coincidence. Candidates hoping to court such states will pay attention if Mr Steyer can demonstrate that campaigning on climate can win elections there. By that time, whisper some, Mr Steyer may be mulling a run for office himself. In 2018 the race to be California’s governor is likely to be open; the Senate is another possibility. Neither campaign would come cheap, but that should not present difficulties.

http://www.economist.com/news/united-states/21600697-tom-steyer-betting-campaigning-climate-change-can-win-elections-verdant