We investigate how competing business interests shaped congressional voting on the American Clean Energy and Security (ACES) Act of 2009. Merging establishment-level data with rollcall records, we find that districts with more carbon-intensive (“Brown”) firms were less likely to support ACES, while districts with more clean-tech (“Green”) firms showed higher support. Conservative representatives responded more strongly to local business interests, though mobilized public opinion could mitigate this effect. Using falsification tests and a Bartik-style instrument based on the shale-fracking boom, we demonstrate that our findings are robust and plausibly causal rather than coincidental.