A petition has been launched by AllOut.org to deliver a thank-you card to US President Barack Obama for his support for marriage equality for gay couples.

AllOut.org aims to put 100,000 names on the card, to be delivered to the president tomorrow.

Mr Obama gave his support to marriage equality yesterday in an interview with ABC News, becoming the first sitting US president to support the move.

The last two Democractic presidents, Jimmy Carter and Bill Clinton, have both spoken out in support of allowing gays to marry.

The petition, which has been signed by over 52,000 people at the time of publication, says: “Thank you for standing up to boldly say that all love is equal.

“This is an incredible, historic moment with huge implications for all nations. As many US states continue to ban marriage and 76 nations criminalize people because of who they love, your leadership takes this issue to the next level.

“Together, we support you in challenging attacks as they come.”

Andre Banks, Executive Director of AllOut.org said: “This is an incredible, historic moment with huge implications globally and in the U.S. As many countries around the world continue to ban same-sex marriage and 76 nations criminalize people because of who they love, President Obama has just stood up to boldly say that all love is equal.

“This story is going to be told around the world and President Obama – and journalists on every continent – must know that millions are on his side.”

Mr Obama told ABC News yesterday: ”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.”

Celebrities have joined gay equality advocates to voice their support on Twitter.

Talk show host Ellen DeGeneres tweeted: “Thank you President @BarackObama for your beautiful and brave words. I’m overwhelmed.”

Jane Lynch said: “Pretty darn happy today. Thanks Mr President, for supporting the dignity of my family and so many others!”

Lady GaGa added: “Obama, congratulations on being the first sitting President to support marriage equality. Feels like the future, and not the past.”

To sign the card, visit www.allout.org/thanksobama.