Caller id is "LINDSAY VW DUL". They leave no message.
I call back after hours (using *67 to block my number). Their message identifies them as the "Conservative Majority Fund". There is a lengthy description of what they do. There are 3 options: donate/obtain info, contact their headquarters, and Do-Not-Call list (I never do this as it can make things worse).
The format of this is near identical to that I've seen for Citizen's United. They probably both use the same hired-gun telemarketing firm."