Romney/Ryan lost WI to Obama 53% to 46%. Ryan did not help very much being on the ticket in WI. WI has gone Dem in the last 7 Presidential elections. I have no doubt that Hillary will carry WI in 2016.
A lot of people from other parts of the country have a huge misconception about Wisconsin as a slight moderate Democrat state. That is not the case and disproved by our conservative Republican Governor, GOP-controlled Assembly & Senate, and a 5-2 conservative majority on the state supreme court.
In truth, Wisconsin is both a strong conservative and strong liberal state. The areas within the city limits of the People's Republic of Madison & Milwaukee are as liberal as San Francisco & Chicago respectively. Other than those islands (plus a few former union manufacturing towns like Racine, Kenosha & Janesville), the eastern 2/3 of the state is extremely conservative. The rural west and Northwoods part of the state tend to be far less ideological and are more moderate.
The general rule of thumb in Wisconsin is: when the GOP runs a conservative, they win and when the GOP runs a moderate, they lose.
Romney ran as a centrist and was too moderate to win in Wisconsin - even with Ryan on the ticket. Cruz is a conservative and will win here.
Also, Hillary is not Obama. She is not black and the black vote will not be there this fall. She is also not Bernie and the student vote will not be energized.
But, the hidden factor that will help Cruz win in Wisconsin in November is the new voter photo ID law. Every presidential election the DNC sends busloads of minorities from Illinois to vote in the central city black neighborhoods of Milwaukee, Madison, Racine & Kenosha. There are some Milwaukee central city precincts and Madison student precincts that have recorded as much as 107% voter participation.
With a voter photo ID requirement, that can't happen this year.