Toespi, it is harder for me to believe Obama will get 55% of the popular vote than to believe McCain will win. I can see him getting around 50%, but he is not going to get 55%. The crowds you mention are irrelevant, as Gore (Tom Petty), and Kerry (Springsteen, Mellencamp, Sheryl Crow) all had massive 50,000 to 80,000+ rallies all over America.
So, based on estimates of 130 million voters in this election, the clowns at Gallup think 13 million more Dems will vote than Pubs?! The numbers were even in 2004 for crying out loud!