Comment Jonathan Coulton Tweeted about getting one. (Score 4, Informative) 468
Which you can read about here. And his letter didn't come from a PAC, it came from the Democratic Party.
I've never gotten anything remotely like this letter from the Republican Party or a conservative PAC (and I probably get well over 200 begging direct-mail solicitations a year).
I don't see such intimidation tactics as paying off for them...