Need a landslide?

What has always been perplexing is the simple question...if the approval rating for the president is so low, why isn't it obvious that the other party [democrats] should be a lock in the mid-term and even presidential elections. This article in the New Yorker was an interesting read, but I'll leave you with one excerpt here:

In a normal democracy, given the state of public opinion and the record of the incumbent government, it would be taken for granted that come next Tuesday the ruling party would be turned out. But, for reasons that have less to do with the wizardry of Karl Rove than with the structural biases of America’s electoral machinery, Democrats enter every race carrying a bag of sand. The Senate’s fifty-five Republicans represent fewer Americans than do its forty-five Democrats. On the House side, Democratic candidates have won a higher proportion of the average district vote than Republicans in four of the five biennial elections since 1994, but—thanks to a combination of gerrymandering and demo-graphics—Republicans remain in the majority. To win back the House, Democrats need something close to a landslide. Their opponents, to judge from their behavior, seem to think they might get one.