Via a comment on Paul Krugman's blog, this excellent blog post, that shows the red states command a higher per capita Congressional influence than the blue states, and that ends up in the United State of moochers, where Congress takes more from blue states than it gives to them in taxes, and gives more to red states than it takes from them in taxes.
It's evident that congressional influence is a large factor. Notably, each of the five most underrepresented states, regardless of political lean, all give more than they contribute. Over-represented red states are more likely to take more (all 18/18), while over-represented blue states are split evenly between givers and takers (5/10). This plot is perhaps the most damning of all for Republicans: it suggests that the only reason that any red states contribute more than they take is just because they don't have the congressional influence to grab more money from the Federal Trough, while blue states exercise fiscal restraint, even when they have the congressional influence to grab more money. Again, the implications are clear: Republican politicians greedily rake in as much money as they can for their states, while Democratic politicians govern toward some other goal, perhaps "the best interest of the country"? In the background of the figure we again see "Redland" and "Blueland", where Blueland has more people but less congressional influence, and therefore pays tribute every year to Redland. In fact, each citizen of Redland has 26.4% more congressional influence than a citizen of Blueland, which corresponds quite closely to their 26.4% higher Mooch Factor.