I don't know how many have noticed, but I was just over at Rasmussen, and when I see the internals, it does appear that he is overweighting Democrats by 3-4% not only in the horse race but in some state polls. For example, his newly released Iowa poll has Kerry up 3, HOWEVER, Bush gets 1% more R's than Kerry gets D's and they are tied on independents. I remember reading yesterday similar discrepancies in the horse race poll.
" Bush is the choice for 88% of Republicans, 13% of Democrats, and 41% of unaffiliated voters. Kerry is preferred by 81% of Democrats, 9% of Republicans, and 42% of unaffiliated voters."
Here's what the Iowa poll said:
" Kerry has secured the vote from 87% of Iowa Democrats while Bush has done the same with 86% of the state's Republicans. Among those who are not affiliated with either political party, it's tied with each candidate earning 42% of the vote. Last month, Kerry held the lead among Iowa's undecided voters, 43% to 39%."
Haven't looked at all the other state polls but wouldn't be surprised that this trend was prominent in Rasmussen's polling. For the horse race numbers, a balanced weighting should put Bush up by 5 or so. Everyone who reads Rasmussen's polls should be aware of this bias.