The 2012 battlegrounds: Wisconsin

It's been more than two decades since a Republican presidential candidate has won Wisconsin - Ronald Reagan in 1984 was the last. In 2008, President Obama prevailed over then-GOP nominee John McCain in Wisconsin by almost 14 points. But Mitt Romney's choice of Wisconsin Rep. Paul Ryan as his running mate may help him wrest the Badger State (and its 10 electoral votes) from Mr. Obama's grasp in 2012.

Wisconsin is a classic midwestern industrial state - slightly whiter than the nation as a whole, with several urban areas, sizable rural areas, and a fairly robust organized labor presence. The unemployment rate in Wisconsin, at 7.3 percent, is half a point below the national average.

Manufacturing and industrial policy play an animating role in Wisconsin politics. The state, while no Michigan or Ohio, is tied fairly heavily to the auto industry, and voters there are particularly attuned to labor and trade policy disputes, including the power of labor unions and the management of trade relationships with other countries like China.

Wisconsin Republican Gov. Scott Walker survived a recall election in June 2012 after his move to restrict the collective bargaining rights of public employee unions provoked a fierce backlash from organized labor. The recall election energized and polarized Wisconsin's electorate, providing a preliminary dry run of the presidential election in November.

Ken Mayer, a political scientist at the University of Wisconsin-Madison, downplays the idea that the recall election result augurs a Romney victory: "The recall probably has had an effect, mobilizing Republicans and leading to a narrower margin than what would otherwise be seen, but it does not look like there was sustained momentum coming out of that election." Mayer predicts that "Obama will carry Wisconsin by a fairly narrow but clear margin."

The Obama campaign has spent almost $8 million on ads in Wisconsin, while Romney's campaign has spent $6.2 million. But Republican outside groups have far outspent their Democratic counterparts - a Romney-aligned SuperPAC Restore Our Future, Karl Rove's Crossroads GPS and the Koch brothers' Americans for Prosperity have spent over $16 million combined. Wisconsin ad spending by outside groups supporting Obama has just exceeded a comparatively paltry $2 million.

The candidates have each visited the Badger State two times since Romney declared himself the presumptive Republican nominee at the end of April.

Polls show the candidates are neck-and-neck in Wisconsin, with Mr. Obama outpacing Romney by 2.3 points in a RealClearPolitics average of polls.