Is so, it makes sense that the sample is going to be skewed towards Republicans if Bush is in the lead because many people who don't really have a party affiliation are going naturally say they are Republicans after deciding they are voting for Bush.
I see Republicans and Democrats complaining about "the sample" after seeing a poll that disagrees with them but I'm not sure it really matters.
Republicans 94 4
Democrats 14 82
Independents 45 40
From the same poll. I edited out the cretins voting for Nader. Left column is W, right is Lurch. Note the number of Dems crossing party lines. I think this is the most important bit of the poll.