ST. PAUL  (AP) - The parents of a gay Minnesota soldier who was killed in Afghanistan are launching a statewide tour by veterans against a gay marriage ban.

Jeff and Lori Wilfahrt's son, Andrew, died in 2011. They planned to appear at a kickoff event Tuesday at the Capitol to talk about how he would have been affected by such a ban.

Rep. Tim Walz, himself a National Guard veteran, is also expected to be there.

A proposed constitutional amendment on the November ballot would define marriage as between one man and one woman. Minnesota law already makes gay marriage illegal, but amendment supporters say the law could be overturned.

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