As you all surely know, the Senate is not a terribly democratic institution. A voter in Wyoming -- population 533,000 -- has about 70 times more ability to influence the Senate's direction than one in California -- population 36.8 million. And the lack of representativeness can be particularly acute when the Senate is conducting business at the committee level. Max Baucus's Table for Six, for instance, which may very well determine the fate of efforts to reform health care, is made up of members who collectively represent about 6.5 million people, or around one-fiftieth of the country's population.
This in and of itself is problematic for Democrats, since there is a correlation between the size of a state and how Democratic it tends to vote in elections for national office, although the relationship is not as strong as you might posit (Rhode Island, Delaware and Hawaii are small states too). The bigger and more structural problem, however, may have to do with the ways that small-state senators raise funds, and in turn, whose interests they are beholden to.
The chart below details the 20 current senators who have received the highest percentage of their campaign contributions since 2003 from corporate PACs, based on data compiled by the Center for Responsive Politics. This data focuses on corporate PAC contributions and individual contributions only; other, usually minor sources of income (self-financing, transfers from other campaign committees, contributions from ideological and labor PACs) are treated as ambiguous and are ignored. Data should be current through roughly May of this year.
What do these senators have in common? All 20 come from states with below-median populations. In fact, you have to go to #26 (John McCain) to find a senator from a state with an above-median population, and #30 (Saxby Chambliss) to find one from a state with an above-average population.
The reason this occurs is because individual contributions are easier to obtain in states with larger populations. Although some people make campaign contributions to candidates from outside their states, most do not, and so a senator from Texas ought to have an easier time eliciting funds than one from Idaho. On the other hand, there is no relationship between the amount of PAC contributions and the population of a senator's state; PACs know that one senator's vote is just as good as another.
What this means is that senators from small states tend to be relatively more dependant on special-interest money -- it makes up a larger share of their overall take. Senators from the ten smallest states have received, on average, 28.4 percent of their campaign funds from corporate PACs, versus 13.7 for those in the ten largest. There is a tendency to think of senators from small states as being populists, and there are a few instances in which this is accurate -- Jon Tester of Montana and John Thune of South Dakota, for instance, are relatively non-dependant on PAC money. But for the most part, something the opposite is true, and senators from small states in fact have more incentive to placate special interests.
It is worth noting, by the way, that the six senators on Baucus's mini-committee are especially egregious in this regard. They rank #1 (Mike Enzi), #6 (Chuck Grassley), #11 (Kent Conrad), #13 (Baucus), #14 (Jeff Bingaman) and #20 (Olympia Snowe) in the share of contributions received from corporate PACs (an average of 47.5 percent of their funds overall).
One can think of several plausible reforms to redress this imbalance. For instance, corporations might be restricted from donating PAC money to a senator unless they do a material amount of business in her state. In addition, the proliferation of the Internet as a fundraising tool has probably leveled the playing field some, making it easier for populist-ish candidates like Tester or Jim Webb to receive contributions from activists all over the country.
This goes a long way toward explaining, however, why the Senate tends to be more protective than the House of corporate interests -- be they in the form of bank bailouts, tax breaks, or whatever else (consider, for instance, that H.R. 1424 -- the second take on the bank bailout -- was approved with the votes of 74 percent of the Senate but just 60 percent of the House). We don't need vague notions about the "cultural" differences between the two chambers to explain this -- they have mostly to do with where the money is flowing in from.
A complete list of the source of campaign funds for all 100 senators follows below.