Hillary Clinton came under fire from progressives this month after her Democratic primary rival, Sen. Bernie Sanders, claimed that she had “received $4.5 million from the fossil fuel industry” — a charge that dovetails neatly with Sanders’ sustained and effective criticism of Clinton’s ties to Wall Street. The charge clearly riled the former secretary of state: “I am so sick of the Sanders campaign lying about me! I’m sick of it!” Clinton told a Greenpeace activist who challenged her at a campaign rally.

Clinton was perhaps justified in losing her temper: neither she nor her rival have taken money directly from fossil fuel companies, since doing so would violate campaign finance rules. Sanders’ claim, based on a Greenpeace analysis, included cash raised by lobbyists with ties — some of them only tangential — to the fossil fuel sector. It also conflated donations to Clinton’s campaign with donations made to pro-Clinton super PACs, over which Clinton theoretically has no control. 

A more accurate accounting of Clinton’s financing, according to FactCheck.org, suggests that the ex-FLOTUS received just $309,101 in donations from oil-company employees, including lobbyists, plus another $161,600 in contributions bundled by lobbyists with fossil-fuel ties. That might be more than Sanders feels is appropriate — and about six times more than the Vermont senator has accepted from similar sources — but it still accounts for only 0.3 percent of Clinton’s total campaign financing.

Clinton’s haul is also only a tiny proportion of Big Energy’s spending in the 2016 cycle. So far, individuals with ties to oil and gas companies have donated at least $17,147,545 to presidential hopefuls — but almost 98 percent of that amount has gone to Republican candidates, with ex-Gov. Jeb Bush alone netting $10.7 million from the sector to bankroll his failed presidential bid. The sector’s spending will climb further as the general election gets underway: over the course of the 2012 election cycle, fossil-fuel donations reached more than $79 million, with 89 cents of every dollar donated going to Republican candidates. 

The industry’s largess is easily explained: by some calculations, the sector receives $119 in federal production and exploration subsidies for every dollar it spends on lobbying, and surely hopes for a similar ROI on its presidential campaign donations. By and large, the oil and gas industry funds the campaigns of the candidates it believes will support its cause — and if that means giving more to Clinton than to Sanders, it also means giving vastly more to Republicans than to Democrats. 

Perhaps more surprising is the fact that the opposite dynamic isn’t playing out in the clean-energy sector. Democrats are, generally speaking, far more climate-aware than their GOP counterparts — yet the Solar Energy Industries Association has given $28,000 to Republican congressional campaigns so far this cycle, and just $15,000 to Democrats. The American Wind Energy Association, meanwhile, has given $52,000 to Republican lawmakers and $35,500 to Democrats. In all, clean energy companies have poured $927,119 into congressional races, according to the Center for Responsive Politics, with a fairly even split between Democrats and Republicans. 

Clean-energy companies’ willingness to bankroll Republican campaigns might be a sign of firms favoring pro-business candidates; it might also reflect the political realities of buying influence in the Republican-controlled House and Senate. In any case, presidential donations are more clearly skewed towards Democrats: the alt-energy sector has given just under $208,000 to the 2016 candidates, with $110,000 going to Hillary Clinton, just under $11,000 going to Bernie Sanders, and about $62,000 being split among the entire roster of Republicans. Donald Trump didn’t get a dime; the campaigns of Gov. John Kasich and Sen. Ted Cruz, his two chief rivals, netted only a couple of thousand dollars apiece.

That’s pocket change compared to the money being splashed about by fossil fuel companies, of course. Indeed, while few progressives are clamoring for more money in U.S. politics, the big question for investors might be why more clean-tech companies aren’t holding their noses, opening their wallets, and trying to counter fossil-fuel cash with lobbying and campaign donations of their own. A case in point: offshore-wind pioneer Dominion Resources spent millions on lobbyists as it fought for the right to install turbines off the Virginia coast, and in the process won approval far more easily than beleaguered rival Cape Wind, which has been remarkably reluctant to grease the palms of political decision-makers. 

Some deep-pocketed investors are taking matters into their own hands in a bid to shape the conversation around climate change and clean energy: billionaire climate activist Tom Steyer has poured at least $13 million into his super PAC, Next Gen Climate Action Committee, making him the second deepest-pocketed mega-donor of the cycle to date. Still, for every Tom Steyer or Michael Bloomberg, there’s a Koch brother or a Ken Griffin: all told, millionaires and billionaires with fossil-fuel ties have spent upwards of $100 million in the 2016 race to date, according to a recent Greenpeace analysis. 

The bottom line is that if money is political speech, then for the time being, the fossil fuel industry is speaking far louder than the clean energy sector. Still, investors should keep a close eye on clean energy companies’ political spending, if only as a proxy for the degree to which such companies are establishing themselves as serious corporate players. If the day ever comes when liberals such as Bernie Sanders feel the need to rail against the pernicious influence of Big Solar or Big Wind’s campaign donations, it’ll be a sure sign that clean energy has well and truly entered the political mainstream.

Ben Whitford is the U.S. correspondent for The Ecologist. He has written for the Guardian, Newsweek, Mother Jones, Slate, and many other publications.