Nate Silver calls Scott Brown's chances at Senate return "even money." [View all]

[WilliamPitt]

Despite all that, it is difficult to view Mr. Brown as much better than even money: he is a Republican in Massachusetts who lost an election by a reasonably clear margin just last month. And if Mr. Brown wins, he could well face another competitive election in November 2014, when Democrats will have more chance to gear up from the race – and when Mr. Patrick will have finished his second term as governor and might be more likely to run for the Senate.

http://fivethirtyeight.blogs.nytimes.com/2012/12/20/for-scott-brown-a-third-round-in-the-battle-against-partisan-gravity/

...and that's before anyone has actually stepped up to declare their intent to run.

Chill.