I can see myself endorsing Feingold.
This will more than likely be a state that will flip to the Democrats in 2016.
Huff Post list these main factors as advantages to a Feingold win :
1.) Democratic turnout tends to spike in presidential election years.
2.) Recent polls have underscored that Johnson is one of the most vulnerable sitting GOP senators.
3.) My personal factor: The wacky Tea Party movement is now in decline compared to years past (Sen. Ron Johnson R-Wis., defeated Feingold during the tea party wave of 2010).
Here is some recent poll information:
A Marquette Law School poll released in mid-April found Feingold leading Johnson by 16 points in a hypothetical match-up, and a March poll by Public Policy Polling found Feingold ahead of Johnson by 9 points.
For the full Huff Post article :
http://www.huffingtonpost.com/2015/05/14/russ-feingold-senate_n_7279800.html?ncid=edlinkushpmg00000090