"He was at a family member's event," Walker said of his son Alex Walker's participation. "This was not a policy statement on his behalf. This was something where he was with a family member. This is a family member we love dearly."
Walker has a long history of opposing same-sex marriages and voted in 2006 for the state's constitutional ban. A federal judge on June 6 declared the ban unconstitutional, and for one week, clerks around the state issued marriage licenses to same sex couples before the judge put the order on hold.
On June 9, Shelli Marquardt, the first cousin of Walker's wife, Tonette, married Cathy Priem at the Waukesha County Courthouse. Alex Walker was one of two adult witnesses to the wedding, which was one of more than 500 held across the state. Walker said he was in New York and did not attend the ceremony.
Walker said he had no problem with his son acting as a witness, saying "He doesn't need my blessing to do anything he does."
Walker, who is running for re-election this fall and considering a 2016 bid for president, said last month that his opposition to gay marriage doesn't matter because the governor plays no role in changing the constitution. But he has been supportive of Republican Attorney General J.B. Van Hollen's defense of the law in court.
Van Hollen has said the same-sex marriages are not legally valid, but those challenging the ban have said they should be recognized. The American Civil Liberties Union is considering filing a lawsuit.
Walker's opponent for re-election, Democrat Mary Burke, supports allowing same-sex couples to marry.
"I believe two people who are committed and love each other should be able to get married," Burke said while campaigning in Mazomanie. "I think Scott Walker needs to be clear with the voters where he stands."