If you want to understand why Democrats are the minority party in Congress, look at four states: Virginia, Tennessee, North Carolina and Kentucky. Before the 1994 elections, when Democrats still controlled both chambers, these Southern states had 24 Democratic House members and 14 Republicans. Among senators, there were five Republicans and three Democrats. Today, there are 24 GOP House members and 15 Democrats, and all eight senators are Republicans. Democrats acknowledge that their prospects for regaining control are dim until they start winning elections in this region. Several of this year's races are lab experiments in this effort, with Democrats...