50 in '10:

Race Rating Change: Castle’s Senate Bid Sets Up Key Race (Greg Giroux, 10/06/09, CQ-Roll Call)

Delaware Rep. Michael N. Castle , a prominent Republican centrist, announced Tuesday that he is running for the Senate seat formerly held by Vice President Joseph R. Biden Jr. The decision by Castle, a longtime fixture in Delaware politics, was a victory for Republican strategists in a Democratic-leaning state.

Castle’s 2010 candidacy, widely seen as crucial to Republicans’ hopes of competing for the seat, has prompted CQPolitics to change its rating on the race to Leans Republican.