The John Edwards who last week announced his candidacy for the Democratic presidential nomination is a very different contender from the fresh-faced young senator who in 2004 bid for the party nod and eventually secured a place on the fall ticket as the vice presidential nominee. By any measure, Edwards has a lot more to offer progressives than he did in 2004. That potential to appeal to the party's left flank is essential for the former senator, who will need an ideological base as he struggles for attention in a race where while Edwards runs strong in polls from early...