Republicans really want Rep. Michael Castle (R-DE) to run for Senate (attempting to secure Joe Biden's old seat). Barring that, they really want him to stay put in the House (he's contemplating retirement). Delaware is fertile territory for Democrats, and Castle, an eight-term incumbent whose district encompasses the entire state, represents far and away their strongest state-wide candidate for any race.
But you got to wonder after this experience whether he really wants any more part of the contemporary GOP. Castle's a lifelong moderate -- it's one of the reasons he's essentially untouchable in what is a solid blue district. But particularly if he ran for Senate, he'd have to come face to face with the fever-swamp that is the GOP base, and I doubt that Castle finds it any less sickening than I do. For a guy already contemplating retirement, this is really the sort of moment that I can imagine pushing him over the edge.
It's not your party anymore, Mike. Let it go.