From this study:

75% of Bush supporters continue to believe that Iraq was providing substantial support to al Qaeda, and 63% believe that clear evidence of this support has been found. Sixty percent of Bush supporters assume that this is also the conclusion of most experts, and 55% assume, incorrectly, that this was the conclusion of the 9/11 Commission. Here again, large majorities of Kerry supporters have exactly opposite perceptions.

There's more. It's worse. It's also clearly a partisan result, though I know nothing about the surveyors. They may or may not be partisan.