Generally speaking, sports fans don't like partisan politics mixed with the spectacle. I remember John Kerry was loudly booed at Fenway—in a town he would win by a landslide—when he threw out the first pitch(which hit the dirt in front of the plate). I got the impression the booing wasn't because it was Kerry or that he couldn't throw. It was about fans not wanting the game polluted by politics.
Nascar picked John Cena over Willard Romney who had traveled down to Daytona to start the race.
Good choice.