I was born in 1971, and the first president I remember is Jimmy Carter. I "campaigned" for his re-election in 1980, and at such a tender young age I learned that my candidate would nearly always lose. Twelve years of Republican rule molded my young mind into believing that it was impossible for Democrats to win. I was stunned when Clinton won in 1992, and flat out didn't believe the polls that said Clinton was trouncing Dole before the 1996 election.
Nowadays, Democrats seem to have the opposite problem. They are dancing on the graves of folks like Karl Rove (who, by the way, can't dance) and Bush 43. A word of advice from a dyed-in-the-wool pessimist: Not so fast.
Although conservatives are seriously unhappy with their stable of candidates, their people are still dogging the Dems in imagined head-to-heads. In a recent TIME poll, Hillary Clinton loses to John McCain, 42%-48%, and to Rudy Giuliani 41%-50%. Even though Dems favor Clinton over Obama, he fares better than Clinton does against Republicans. TIME has Obama losing by a hair to either McCain or Giuliani. (This despite Firefighter-gate! Astounding!)
TIME attributes the surprising (though not to this hardened loser) results to the fact that the voters shedding their loyalty to the Republican Party don't think of McCain or Giuliani as, you know, Republicans. (I wonder how they feel about that? It's like having your white friends tell you that you're the special black guy! You're OK!)
On the other hand, it may be that Clinton, whom voters know and, err, love, has reached her maximum percentage potential, but that Obama and Edwards still have room to win over additional voters.