Having listened to the Norm Coleman ad going after Franken for "juicy porn" , I have to wonder how well it would work.  
Minnesotans are a bit touchy about having their accent mocked - and particularly when it's done poorly.  You have no idea how many people were pissed off by Fargo and refused to even see it. 
Coming from Minnesota, I am familiar with the accents of the different regions from the North Woods where I am from to the Range to the Cities and nowhere have I heard that accent anywhere in the state. The person speaking sounds like an ignorant buffoon. 
I think this is a case of a New Yorker (Coleman) not getting Minnesota and perhaps looking down on the state as provincial and backwards. I cannot see it being effective with anyone who is not already disposed to vote Republican.