Minnesota's four major party candidates for U.S. Senate debated agriculture policy, as well as federal spending for nursing homes and the military, today at Bethany Lutheran College in Mankato. Constitution Party candidate David Swan brought a radically different perspective to such now-familiar topics as social security, calling such government programs unconstitutional and saying they should be eliminated. Meanwhile DFL candidate Mark Dayton predicted a bitter conclusion to the Senate race, and Republican incumbent Rod Grams defended his use of negative ads. Minnesota Public Radio's Amy Radil reports.