Voting records indicate how a politician perceives a given context, and the voters make their choices dependent upon whether they like how the candidate makes those perceptions. After 20 years in the Senate, we can make a pretty good guess at where John Kerry stands as it relates to military spending, health care, etc. And those stances are quite liberal. After only a few years in the Senate, the only conclusions we can draw about Edwards is that he is extremely liberal.
Every time the Republicans bring up John Kerry's voting record, the Democrats accuse them of playing dirty politics and making personal attacks. So there must be something wrong with his voting record, no?