Adding to the Democrats’ woes is the unpopularity of the Obama administration. The president’s net job approval is now negative, with more Americans disapproving than approving of his performance. President Obama has certainly “earned” this poor approval, thanks to three significant, unforced errors. First, his economic stimulus fell far short of expectations because he underestimated the depth of the recession and overestimated the effectiveness of the pork-laden stimulus bill that Congress passed. Second, he has wantonly inflated and made no serious effort to reduce the budget deficit, now an acute concern for many Americans. Third, he passed a health care bill that was and remains highly unpopular.

Any one of these issues would give Republicans a decided advantage this year. The combination of all three creates the kind of electoral environment not seen since 1974, when Democrats annihilated Republicans because of Watergate and recession.

Finally, Democrats face the added burden of an inefficiently distributed base of voters. The Democratic base consists mostly of union workers, upscale urban liberals, and minority voters, many of whom are clustered in highly Democratic districts. While Democrats have a congressional majority in many other districts nationwide, it depends upon independents and soft partisans, the sorts of voters who split their tickets. These voters have bolted the Obama coalition in droves, leaving scores of Democratic incumbents in jeopardy.