Biden vs. Castle?

ABC News’ Jonathan Karl reports: Republican Congressman Mike Castle — a popular former two-term governor who has served as Delaware's sole member of House for 17 years — is expected to announce today whether he plans to run for Senate.  He has called a press conference in Wilmington, Delaware today at noon. UPDATE: Castle is running for Senate, a GOP official with knowledge of his plans tells ABC News. Castle has been considering a run for Senate, a prospect that would likely pit him against Beau Biden, the Delaware AG, Iraq War veteran and son of the vice president. It would be quite a race. Castle hasn't lost an election since he was first elected to the state legislature in 1966. Biden hasn't announced his intentions, but he is expected to run for Dad's old seat. Republicans are hopeful that Castle will announce he is running. A top Democratic operative tells me, "It doesn't smell good for us."Castle's office isn't talking; they won't even say why he is holding the press conference.