Kerry can't pick someone from Mass. The Constitution forbids members of the electoral college from casting a ballot that has a President and Vice-President from the same state. In the 2000 chaos, the dems tried to show Cheney was really from Texas.
Kerry ought to pick Edwards. Edwards is young and a good campaigner and fundraiser. Not only could Edwards help the dems win North Carolina, it also might help them retain Edwards's Senate seat.
Kerry should select someone for geographical and ideological balance. In the old days, a northern liberal Democratic would have chosen a southern conservative Democrat. Today, its hard for the Democrats to find someone who can bring that kind of balance to the ticket. If I were Kerry, I'd pick the other Democratic Senator from Florida. Its the best he can do and he needs Florida's electoral votes if he wants to win the White House
Lottery law Edwards has lost credibility in NC. Even the Civil War Democrats are getting tired of him.
Edwards can't help Kerry win N.C., not anymore than Gephardt can help Kerry win Missouri.