President Obama became the first sitting president to voice his support for same-sex unions today during an interview with ABC News' Robin Roberts. ABC aired a short clip today at 3:00 p.m., where Obama laid out his reasons for his support of marriage equality for gay and lesbian couples.

I hesitated on gay marriage in part because I thought civil unions would be sufficient. I was sensitive to the fact, for a lot of people, the word "marriage" invokes powerful religious traditions. Over the course of several years, as I've talked to friends and family, when I think about members of my own staff who are in committed monogamous relationships, raising kids together, when I think about soldiers, airmen and Marines out there fighting on my behalf who feel constrained because they're not able to commit themselves to marriage ... for me personally, it is important to affirm that I think same-sex couples should be able to get married.

The full interview is scheduled to air tonight at 7:00 p.m. on ABC's World News Tonight and will be featured on tomorrow morning's Good Morning America.

Stay tuned for more.