It would be interesting to see if Kirk could become the Kay Hagan of 2016: good campaign, flawed challenger, personally inoffensive, but still taken down by the environment and electorate.
The thing going against Hagan was the fact she voted with Obama 96% of the time and Obama's popularity being underwater. Kirk won't have that against him.
In addition, he has a distinct advantage over Hagan of being a true moderate able to engage in bipartisan initiatives. And if some of those initiatives become laws, that’s something he can tout in 2016.
