Romney on air in Wisconsin, next likely battleground

The ad flashes slogans like "proven fiscal conservative" and "boldest GOP agenda since Reagan '80" while it plays clips from a Romney speech in which he says his business experience helped him cut spending in Massachusetts.

"The principles of business work in government and it's high time to bring those principles of fiscal responsibility to Washington, D.C.," Romney concludes in the ad.

Romney's campaign did not immediately respond to a request for how much money it was spending on the ad.

Wisconsin's April 3 primary is most likely the next big Republican battleground — Romney has done little to try to win Louisiana's Saturday primary, and Rick Santorum is unlikely to do well in suburb- and centrist-dominated Maryland, which also votes April 3.

Wisconsin's politics are similar in some ways to Michigan's: Many fiscally focused conservatives in the suburbs in the southeast of the state (in this case surrounding Milwaukee), and many more populist, religious and blue-collar Catholic and Protestant voters in the western and northern parts of the state.