David Blankenhorn has recorded a video in opposition to Minnesota's proposed constitutional amendment which would limit marriage to heterosexual couples.

In 2010, Blankenhorn, the founder and president of the conservative group Institute for American Values, served as an expert witness in favor of California's gay marriage ban at the trial challenging the constitutionality of Proposition 8. And he argued against gay nuptials in his 2007 book The Future of Marriage.

But in a New York Times op-ed published in June, Blankenhorn reversed course.

In the 2-minute video released Thursday, Blankenhorn says the amendment would harm society.

“I came to a stronger appreciation in my own mind of the importance of accepting gay and lesbian people and couples,” he says. “There are powerful reasons to believe that we will be a better society if we include gay and lesbian people and their relationships as full and equal parts of society.”

“If you just bam put it in the constitution, forever and a day it's going to be this one thing. I think it's very harmful. Very harmful. Now let's try to learn to share this space that we have together.” (The video is embedded on this page. Visit our video library for more videos.)