He pretty much kept to the more populist "the people vs the powerful" thing until the end.  The one thing where I think the Bush campaign kicked the shit out of the Gore campaign--one of the only things--was how they played the press after the first debate.  That ended Gore's momentum, and his completely different approaches to the three debates--smarty pants, contrite, and finally measured but still not sufficiently aggressive--pretty much kept things static for the last couple of weeks, with the late undecideds breaking toward Gore in the last 5-7 days making the difference.  

Populism got him back in the race, but it couldn't overcome his lack of confidence in deciding on his public persona and sticking with it.  Kerry, otoh, benefitted from his steady and confident public persona--he didn't really try to reinvent himself too much, although the goose hunt was kind of a bust--but his lack of populism is what I think cost him greater support among working class white voters who aren't thrilled with the war or the economy, but couldn't relate to the guy because he didn't talk to their concerns or show that he could inhabit a world view much different than a reticent, New England Brahmin with an olympian temperament who's been in the Senate almost 20 years.