It is also relatively common in America for corporations to donate large sums to the re-election funds of officials already in power; they are often then granted concessions in their favour (e.g. George W Bush was very good to the oil industry, Barack Obama is friendly with coal companies).
While both forms are legal, people are generally more morally comfortable with the first than the second form.
Just to make it clear they can't actually donate large sums of money directly to the candidate's campaign.
http://en.wikipedia.org/wiki/Political_action_committee#Supe...
A not-unimportant percentage goes to political consultants.
In financial markets it is well understood that brokers' fees, though a tiny fraction of transactions, are an important driver of marketing activity. It is widely thought that these fees create dangerous conflicts of interest requiring extensive regulation.
The possibility of similar forces in other arenas is not so carefully noticed.
PETA's goal is not to bribe politicians into enacting pro animal legislation, but to change how people look at the issue or when most people agree with them they can then inform politicians of this so politicians will then 'toe the line' so as not to offend voters.
People with deep but irrational convictions, can be pulled to rationality or vice versa.
I'm not saying this specifically about PETA, but that's generally how campaigning works.
But yeah. 'Round here laws are products, and marketing is a huge part of how they're sold.
1) Awareness raising. A lot of people are partially or completely unaware of what laws are on the ballot, what initiatives actually mean and what the stakes are.
2) Driving turnout. This is actually probably much more important than #1. If you look at the statistics, the percentages of eligible voters who actually vote in elections is not incredibly high. Money can be used to ensure that people who are sympathetic to your cause are properly registered to vote, know where their polling places are, even literally give them transportation if they don't have it. For this issue, to take an example, it is extremely likely that college students are overwhelmingly for gay marriage, but a lot of them are not yet registered to vote, or are from out of state and haven't re-registered in Washington, so this kind of money lets pro-Marriage organizations have a heavy presence on campuses getting kids registered in the state, telling them where they need to go and when to vote, possibly even renting busses or vans if polling places are inconvenient for campuses.