The 10 states that could decide the next Senate
The Senate map for 2016 might not be as bad for Republicans as it looks.
The GOP has a bigger cushion than expected for its new majority, probably 54 seats. More veteran senators may stick around to preserve safe seats. And some vulnerable incumbents will have committee chairmanships that could pump up their profiles.
Even though conventional wisdom suggests this may be a short-lived Republican majority, interviews with nearly two dozen operatives in Washington and 2016 battleground states reveal a more nuanced picture of the next Senate landscape. The most vulnerable Democrats this year were up in very red states; the most endangered Republicans in 2016 will, with the exception of Illinois, be defending seats in purple terrain.
Three sitting Republican senators begin the cycle as underdogs: Wisconsins Ron Johnson, Illinois Mark Kirk and Pennsylvanias Pat Toomey. Obama carried each of these states by at least 5 points in 2012, and there are credible challengers who will likely take little coaxing to get in. The only truly endangered Democratic incumbent is soon-to-be Senate Minority Leader Harry Reid of Nevada.
http://www.politico.com/story/2014/11/2016-elections-key-states-112801.html#ixzz3JCnxFyDM