Demonstrators cheer the effort to recall Wisconsin Gov. Scott Walker on Jan. 17 in Madison. Andy Manis/AP hide caption

itoggle caption Andy Manis/AP

Rick Santorum won the Louisiana Republican presidential primary Saturday, beating front-runner Mitt Romney in the race to challenge President Obama. Jae C. Hong/AP hide caption

itoggle caption Jae C. Hong/AP

A screen shot of President Obama from the trailer for his campaign's movie The Road We've Traveled. BarackObama.com/YouTube hide caption

itoggle caption BarackObama.com/YouTube

Peoria, Ill., as seen from across the Illinois River. Jeff Haynes/Reuters /Landov hide caption

itoggle caption Jeff Haynes/Reuters /Landov

A supporter of Republican presidential candidate Mitt Romney holds a vintage campaign poster of Romney's father, George Romney, in Albion, Mich. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images

Mitt Romney sings the national anthem before speaking at a Tea Party event at the Bakers of Milford Banquet Hall on Thursday in Milford, Mich. Scott Olson/Getty Images hide caption

itoggle caption Scott Olson/Getty Images

Mitt Romney shakes hands with supporters after a town hall meeting at Eagle Manufacturing in Shelby Township, Mich., on Tuesday. Andre J. Jackson/MCT/Landov hide caption

itoggle caption Andre J. Jackson/MCT/Landov