Something worth mentioning in the context of the Citizens United decision, though not directly tied to the issue at hand there, is that a group doesn’t actually need to spend vast sums of money to have a decisive influence on politics. It just needs to be able to credibly threaten to spend said sums. Bank of America, for example, dedicates $2.3 billion to marketing in 2008 so it’s clear that they’ve got the budget to mount a $100 million series of scathing attacks on a Senator who pisses them off and basically laugh that off (and note that in 2004 total spending on Senate campaigns was just $400 million). And if you can have it be the case that just one Senator goes down to defeat for having pissed off BofA then everyone else will learn the lesson and avoid pissing them off in the future. You don’t need to actually sustain that volume of campaign spending.
I’ve seen a lot of jokes about the idea of corporate-sponsored candidates and such. But the real issue here isn’t so much affirmative activity on the part of businesses as it is negative activity on the part of politicians. We’ll be looking at one further step toward a political system in which large business interests have a de facto veto over all policy questions. Politicians will still be free, of course, to have feisty debates about which party is more to blame for the budget deficit, about who loves the pledge of allegiance more, about who’s more determined to pretend that there won’t be bailouts after the next financial panic, etc.