As conservative Republicans tell the tale, the 2006 election was merely a referendum on the Bush administration's incompetence in Iraq and New Orleans and on the Republican congressional scandals. The contest, Washington Post columnist Charles Krauthammer wrote, "was an event-driven election that produced the shift of power one would expect when a finely balanced electorate swings mildly one way or the other." Others insist that demographic trends continue to favor the Republicans. Seeing 2006 as an anomaly, political analyst Michael Barone argued that population growth patterns favor Republican-leaning areas in the interior of the country rather than Democratic-leaning areas on...