I think I’ll step into a great dispute over at TAP between Jamelle Bouie and Monica Potts over the importance of big, outside money in politics. Bouie:

Undoubtedly, the Koch brothers put a considerable amount of money in advancing conservative causes and aiding conservative politicians. But for actual elections, I’m not sure that it has a hugely measurable impact. Any given candidate’s fate has more to do with fundamentals...They can’t shift the tides of public opinion, and they can’t reverse an election result; all they can do promote their ideas to elites, and -- in some cases -- make an electoral environment a little more favorable. 

Potts responds:

I do think that on the macro issues the Koch brothers hold a lot of sway. We know from Jane Mayer’s terrific reporting in the New Yorker that they’ve helped fuel campaigns against items on Obama’s agenda from climate change to health-care reform. Much of that work amounts to a giant misinformation campaign that works to some degree, and if it hasn’t diminished support for the bills entirely, it’s certainly slowed down the speed at which we address those problems. It’s also helped give power to the politicians who support trying to unravel those efforts.

They’re both right! In part. On the one hand, Bouie is correct that outside money, even a lot of it, is unlikely to swing very many votes, or to change support for policies. Health care reform was relatively unpopular in 2010 because Obama was unpopular, and Obama was unpopular mainly because the economy stunk. Money may push things around a bit, but almost always on the margins.

On the other hand, money can make a significant difference in what the opposition talks about, what positions their candidates hold, and who contests and wins primary elections. It was highly likely (perhaps I’d go so far as to say inevitable) that Republicans would oppose Barack Obama’s proposals on climate, and highly likely that Republicans would side with GOP-aligned interest groups on climate/energy issues. What was not certain at all is how Republicans would do so. It seems to me that one plausible outcome would have been for Republicans to agree with Democrats (and the scientific consensus) on climate change, but to demand policies which were much better for GOP-aligned energy interests than whatever Democrats chose to offer. 

Last caveat: it’s often difficult to separate money as a key variable in these things. Politicians respond—in my view, should respond—to major interests within their coalition. The energy industry is a large interest in the US; it hires lots and lots of people, makes major contributes (or not) to economic growth, and will have a lot to do with the future of the economy. It is inevitable that it will be represented, at least to some extent, by at least one of major political parties. Whether spending gazillions of other money to fund think tanks, publicity campaigns, and the rest of it win more representation is an empirical question, but one that does not have an obvious or easy-to-access answer.