Walker doubled down on his stance that the legality of same-sex marriage should be up to the states, and cited a referendum to ban gay marriages in Wisconsin that was passed by voters in 2006. Walker, a potential 2016 GOP contender, argued the nation needs a conservative president who can appoint conservative Supreme Court justices "who will faithfully interpret the Constitution and laws of our land without injecting their own political agendas."
Walker also argued an amendment to the Constitution is necessary to define marriage as between one man and one woman.
"As a result of this decision, the only alternative left for the American people is to support an amendment to the U.S. Constitution to reaffirm the ability of the states to continue to define marriage," he said in a statement.
Walker first suggested a constitutional amendment against gay marriage earlier this month, saying he'd support such an amendment as president.
After the Supreme Court rejected an appeal from Wisconsin to overturn a lower court's ruling striking down the state's gay marriage ban in October 2014, Walker said the fight for a ban in the Badger State was "over," and insisted "others will have to talk about the federal level."