This mechanism may have deleterious effects on our political discourse and decision-making, but it's hard to call something that doesn't involve a politician changing his mind as a result of money "bribery". This mechanism is a systems problem, it seems to me, not a problem with individuals.
Now I'm sure this is far from the only thing that's going on. (In particular, I think I remember Lawrence Lessig talking about how money may or may not buy a change of views, but it surely buys access. You pick up the phone for the guy that contributed $LEGAL_LIMIT to your campaign.) Moreover, I haven't ruled out that the money changed their minds---just provided an alternate hypothesis. Nonetheless, this toy model provides a not-totally-implausible explanation for things we observed, without invoking bribery.
Edited for style.
"In June 1995, Boehner distributed campaign contributions from tobacco industry lobbyists on the House floor as House members were weighing how to vote on tobacco subsidies"
This is, incidentally, also the argument for why insider trading isn't illegal for Congress. It would give the executive branch a huge stick to beat the legislative branch with.
Of course, this doesn't help the problem of poorer candidates trying to run against candidates who are already wealthy to begin with. But I think it could be a start.
There has to be some way to equalize the playing field so that everyone running for office has a voice. Otherwise the democratic process is distorted.
Here's a radical idea: what if we outlaw electioneering? No advertising, no campaigns, just structured dissemination of information via debates and perhaps online charts comparing differences in candidate views.
Two thoughts:
1) What about differentiating between speech in support of an idea vs. in support of a person running for election? This may be useless though, as it still privileges viewpoints held by wealthier individuals.
2) What about restricting political speech to mediums where reach is (mostly) independent of financial input, such as internet forums and public/private meetings? For example, I can post something on Hacker News about a candidate, but I can't pay to get that posting to #1. This is a more egalitarian platform for the dissemination of ideas.
Then you get into the wide gray area of "public interest organizations" that aren't supporting a candidate, just supporting the idea that Obama's birth certificate is fake.
I've come around to the far opposite position on this. The only regulation on any political donations should be transparency. Give as much as you want to whomever you want, as long as it's completely out in the open.
Also: you wouldn't hire someone based on just a resume and a canned promotion video, and YC wouldn't fund a startup based just on an initial business plan, so why would you vote for someone based on the same? Politics is about persuading large groups of people to go along with you. You can't evaluate that from a chart.
I don't think candidates should be prohibited from trying to persuade voters, hence the need for debates. In fact, I would argue that political commercials are more akin to "canned promotion videos" than live televised debates.
Also, I think it's inaccurate to characterize my suggestions as disenfranchising voters. They still have the power to seek out information on the candidates running for office. The only difference here is that biased viewpoints won't be forced upon them in isolation.
How is preventing voters from exposure to one-sided campaign commercials disenfranchisement? If the important thing is informing the electorate, then let's do so in a balanced way.