Here's the problem the Democrats have......their voters are ant-Bush more than they are pro-Kerry. The problem with that is that a protest vote is far less likely to show up at the polls than someone who is voting "for" someone as the Bush voters are doing. Pat Cadell pointed this out repeatedly, that protest voters make a big impression on pollsters but then don't bother to vote on voting day. So add 5 points to any Bush poll number you see.
But then subtract it again to account for fraud. Bush by four if election held today.