Casey's Endorsement Of Obama

Sen. Bob Casey's endorsement of Barack Obama is obviously a shock to Sen. Clinton's campaign. (I'd note that Obama has picked up a total of three superdelegates since last week, to Clinton's zero).

Casey is a freshman Senator; his father, former governor Bob Casey Sr., was so popular among white working class Dems that pundits have named an entire class of voters in his honor: the Casey Democrats who live in the inner suburbs of Pennsylvania's cities, who are wary of liberal social views but very sensitive to economic conditions.

Obama begins a six-day bus tour in Pittsburgh today.