Pundits have lamented the disappear ance of Republican moderates for years. It's time now to lament the disappearance of moderate Democrats. Last month, Sen. Joseph Lieberman announced he wouldn't seek re-election. He lost the Democratic primary in Connecticut in 2006 because of his support of the Iraq war, but won in November as an independent. The irony was that the 2000 Democratic nominee for vice president was re-elected largely by Republicans who spurned their party's little-known nominee. But Republicans seem likely to field a stronger candidate in 2012. Then last week, Rep. Jane Harman announced she'd resign soon to become...