For more than 30 years. DE has been represented by Bill Roth-R,Joe Biden-D,Mike Castle-R and Tom Carper-D.
Longtime career and name recongition is Castle advantage, but
1. His old and Delaware would not benefit from his Senate seniority. And THIS can be a issue there
2. He's a Republican, while Delaware became increasingly Democratic. He's still in House only because he's in DE politics from a long time, but it's not like running for other office
3. Beau also have a famous name
(Lincoln-AR,Bennett-CO,Kaufman-DE,LeMieux-FL,Burris-IL,Brownback-KS,Bunning-KY,Bond-MO,Gregg-NH,and Voinovich-OH are likely to leave office January 2011.
Likely? Burriss, LeMieux, Kaufman (about whose seat we are actually talking about), Brownback, Bond, Bunning, Voinovich and Gregg are not likely to leave. They're retiring.
But I think Lincoln would be reelected.