I would want him but he's a senator, and senators don't win. Look: 1/3 of Wisconsin Reps voted him in 04, only guy to stand up to the USAPATRIOT Act, only Dem to vote to remove Clinton in 99, deficit hawk, populist, social liberal, and from a swing state that is trending GOP.
In the end, I want him to go for VP, with a popular moderately conservative governor from a major swing state (15+ EVs). Doesn't that describe Richardson (bringing in NM, NV, AZ, CO, total 29 EVs)?
Feingold didn't vote to remove Clinton.