You're right, it doesn't exist, and here's why: These polls, at this stage in the game, are comparing apples to oranges. When they ask a person - registered voter, likely voter, merely an "adult", it doesn't matter - "Bush vs Kerry, you pick," what they're doing is asking the person to make a judgment on three years' worth of governance on Bush's side, while asking little more than "Do you think he's a nice guy or not?" on Kerry's side. So of course Kerry's going to get an extra bounce on that, because hardly anyone knows anything about him.
Come September or October, that will change.
Ambrose has been posting a number of threads on FR in the last few days from old Washington Post articles published in 1980 and 1984, showing how, at various points in those election cycles, the polls were predicting all sorts of things that ended up being 180 degrees from what the voters actually did on Election Day.
It's just too early. These polls mean bupkis.