Take a look at RealClear Politics from 2004, although in all fairness those were LV polls, something we don't seem to get in this election cycle. Bush was clearly ahead in those polls as early as the beginning of September 2004. McCain has not shown the same tendency in the 2008 polls.
That's true, but I'm certain that those polls did not weight so heavily in Kerry's favor as the pollsters are in Obama's favor this year.
I did some quick checking on the exit polling from the 2006 election, a terrible year for Republicans. The turnout difference between the parties favored Democrats by 3%, 38% to 35%. Three points. Going back over the past five Presidential elections, the greatest spread in party ID was 4%.
I think it's possible that McCain is behind or that he has a slight lead, but that's impossible to determine from current polling. Any poll that gives the Democrats more than a 4% advantage in party ID is questionable, even Rasmussen, even Gallup, and especially the ABC/WaPo junk that came out last night.