President Barack Obama's coming out in favor of gay marriage is being cheered by gay rights groups.

In an interview with Good Morning America anchor Robin Roberts, Obama said it was important for him to speak out on the issue.

“I have to tell you that over the course of several years as I have talked to friends and family and neighbors when I think about members of my own staff who are in incredibly committed monogamous relationships, same-sex relationships, who are raising kids together, when I think about those soldiers or airmen or marines or sailors who are out there fighting on my behalf and yet feel constrained, even now that Don't Ask Don't Tell is gone, because they are not able to commit themselves in a marriage, at a certain point I've just concluded that for me personally it is important for me to go ahead and affirm that I think same sex couples should be able to get married,” said Obama. (The video is embedded in the right panel of this page. Visit our video library for more videos.)

The president had previously said he supported civil unions and was “evolving” on marriage for gay couples.

The announcement comes just three days after Vice President Joe Biden said he was “comfortable” with gay couples marrying.

Herndon Graddick, president of the Gay and Lesbian Alliance Against Defamation (GLAAD), cheered the move.

“The arc of history today bent a little closer to equality for every American," said Graddick. “After hearing the stories of countless couples and families, President Obama has drawn the same conclusion shared across party lines and by a majority of Americans today: everyone deserves the opportunity to marry the person they love. As our nation draws closer to a more perfect union in which every person is created equal, we are left deeply encouraged by this truly watershed moment.”

Shannon Minter, legal director for the National Center for Lesbian Rights (NCLR), added: “President Obama has once again proven himself to be the strongest and most principled supporter of full equality for lesbian, gay, bisexual, and transgender people ever to occupy the Oval Office. As he has done on so many other issues facing our community, the President showed his great depth of compassion and respect for the struggles faced by same-sex couples and their families and his commitment to genuine equality and justice for all people. This is an unforgettable day in our nation's history, and one that will bring enormous comfort and hope to millions of Americans.”