In fact, the Republicans’ strong position in the House is a surprising consequence of Obama’s electoral coalition. No victorious presidential candidate has depended so heavily on the support of urbanites and nonwhite voters. These are “bad” voters for the House of Representatives: that is, it is very difficult to parcel out urban voters, clustered within cities, across many districts. By contrast, suburban and rural voters, who more often vote Republican, are more spread out and can be distributed across districts so as to maximize a party’s vote. Thus, Democrats regularly win with 80 percent or more of the vote in urban districts, while Republicans win with 65 percent in rural and suburban districts. This means that a larger share of the Democratic vote is “wasted.”

This effect is multiplied by the influence of the nonwhite vote. In 1982 liberal Democrats sponsored amendments to the Voting Rights Act that require state governments to create minority-majority districts whenever possible. This makes it all the more difficult to disperse the Democratic vote. Alabama, Georgia, Louisiana, Mississippi, North Carolina, and South Carolina all have large African-American populations, and the states are legally required to cluster them, producing heavily Democratic districts, rather than spreading them out across swing districts. Ditto Texas, where the Hispanic population is usually concentrated in a handful of south Texas districts, rather than distributed in such a way as to make more seats winnable for Democrats.

Just under a year out from the 2014 midterms, it is difficult to be more specific than this. We will have to wait to see how Obamacare plays out, how the economy performs, and what sort of candidates the parties select to get a firmer sense of the Republican party’s prospects. Still, at this point, it is possible to say that the Republicans hold a fair chance of taking control of the Senate and are favored to retain control of the House.