As lawmakers tee up a constitutional amendment to ban gay marriage, Gov. Mark Dayton said Wednesday that he will oppose it "with every fiber of my being."

The governor acknowledged that he has no say about whether the amendment to define marriage as only one man and one woman reaches the ballot. To get in front of voters, the amendment requires approval from a simple majority of lawmakers. The Minnesota Senate has already approved it, the House will soon follow suit.

Dayton said lawmakers are "ill advised" to move forward with it and predicted it's failure when Minnesotans vote in 2012.

"I think Minnesotans have much more compassion and understanding than they recognize and I think it will be defeated next year," Dayton told reporters.

According to the Associated Press, the House Rules Committee narrowly approved a floor vote on the amendment Wednesday morning. The committee voted 13-12 on the measure, with all Republicans but Rep. Tim Kelly of Red Wing voting to approve.