Okay, so we have 100 voters.
20% are dem
20% are gop
35% are swing
5% are Perot/Nader idiots.
20 vote dem, because they are partisan.
20 vote gop, because they are partisan.
35 vote dem or GOP, with a few voting for the 3rd party freaks as well.
5 vote for 3rd party freaks only.
The end results are the same.