We should bring up Seamus so much that people think he's Romney's running mate. [View all]
Lee Atwater, when managing Bush Sr.'s campaign against Michael Dukakis, said regarding Dukakis that he would "strip the bark off the little bastard" and "make Willie Horton his running mate".
We should be doing the same thing with Romney, regarding his dog Seamus.
It's a story almost any American can understand - abusive treatment of one's dog. It says a lot about Mitt as a person and cements the image of him being a clueless, disconnected asshole.
Polls show voters of all political affiliations say the Seamus story makes them less likely to vote for Romney. It's not exactly controversial and there's zero chance of the Romneys spinning the story to gain sympathy for him. In fact, they've already tried to do so numerous times, and they keep making it worse - like his sons admitting that Seamus ran away after the trip, or his sister mentioning that Seamus ran away from home quite often.
For better or worse, the "likeability" factor is huge in politics, and nothing seals Romney's fate as unlikeable more than the revelation that he abused his own dog.
And unlike Atwater, we don't need to lie, exaggerate, or smear Romney with this story at all. The truth is already about as damaging as it could possibly be.