Yesterday, driving to the Election Judge training, I stopped at 8th and Emerson, east of downtown.  On the back of one of the stop signs, someone had spray-painted, "Kill Bush".
One data point isn't much, and not for a moment do I think the Democratic Party had anything to do with this.  But I've been driving around, glancing at yard signs and bumper stickers, and even graffiti for month.  I have seen protest signs equating the Israeli flag with with swastika, and one - one - Bush sign defaced.  (I bet I know who those people are voting for.)  I have seen reports of other, but I guess a defaced sign makes a worse statement than a stolen sign.
But not once have I seen anything remotely approaching "Kill Kerry."  Nothing, nothing suggesting physical violence against a candidate or his party or even his union thugs.
This is not rational.  Peter Beinart notwithstanding, it doesn't even have rational roots.  And, it's completely one-sided.