Individuals are responsible for doing that - prior to any time they vote.
Sadly, the vast majority just look at the letter next to the name and call it 'good enough.'
I have to say, I believe STRONGLY that outside very poor countries, it is NOT the politicians who are at fault, it is the people who believe and vote by the ads that all those contributions paid for. The lobbyists are not bribing our politicians with money, they are bribing them with ACCESS TO OUR VOTES. If we didn't sell that to the media that run the ads, the lobbyists couldn't sell it to the politicians.
We need to go back to teaching basic logic in school. But as disillusioned as I am by the Democrats these days (I'm a lifelong Democrat until this year) I have seen a HUGE difference between the behavior of the ones we get to IN PERSON vs. the ones whose in-person contacts have only been paid schmoozers from corporations. I also note that hardly any posts I've seen on ECF in the last 2 years have adopted the idea of doing a few hours of IN-PERSON campaigning for people on our side. Just half a Saturday, or a coffee held at your house. It's hard to believe, but I've seen this kind of personal contact make a huge difference in local elections. (I don't think it would do anything for Presidential elections, and in the states that are the size of nations, Senatorial. But anything smaller, YES.)
When we decide our personal efforts would be worthless, that becomes self-fulfilling prophesy. (Now, if I could just learn to BE NICE when I talk to people, I'm sure it would help a lot!)
I believe Senator Boxer is 100% sincere in her stupidity on this topic. Worse, I believe information sent to her is being filtered and censored by young staffers who know 1000% less than the Senator herself.