The thought did cross my mind. Most people assumed that was the reason why Bush the Elder went with Quayle, and we all know how THAT turned out.
On one hand, I can see things going that way, especially if picking Ryan wins Romney Wisconsin. However, I'd be careful with that comparison; Barack Obama is no Michael Dukakis. If Obama's attack on Ryan's budget proposals ramps up, voters might turn against him pretty quickly.

But maybe Obama should have ditched Biden for Eva Longoria or something.