Mainly because the Republicans are better at it.

Perhaps it's because the press is biased to the extreme - have you heard some of the things that Terry McAuliffe is spewing, Jack?
I can't believe you are so naive!

I haven't been called naive in over a decade...
;-)

Seriously, though, that "press bias" thing is getting a bit old. I have been around the block more than once, and from my personal observations, discounting the tendencies of the press and other sources, I am seeing more organized efforts at affecting the election outcome in ways I think are not kosher by Republicans and more anarchic, idiotic behavior (such as those union members trashing a Bush/Cheney campaign office) from Democrats.

Instead of thinking me naive, perhaps reading some rational left-leaning weblogs might show you that not everything said by the right-leaning sources is the absolute truth. There are just as many accusations on the left of the media being biased towards the right, with just as much "evidence" as is presented by right-wingers who accuse the press of being biased towards the left. There are just as many accusations of bad behavior by right-wingers as there are of bad behavior by left-wingers, again with just as much "evidence" presented.

If you only read and hear things from people who "think like you" then your worldview becomes very much colored by those biases. If you think every accusation from the left that the right is behaving badly is a lie, and every accusation from the right that the left is behaving badly is the truth, then I am not the one being naive. There are at least two sides to every story, and I have spent years trying to see all sides. I do see that some accusations of the right-wing about the left are true, but I also see that some accusations of the left-wing about the right are true as well.