US President Barack Obama has ended months of equivocation on the issue of gay marriage by saying he thinks same-sex couples should be able to wed.
He told ABC News: "It is important for me to go ahead and affirm that I think same-sex couples should be able to get married."
Mr Obama has become the first US president to back gay marriage.
In recent days, Vice-President Joe Biden and cabinet member Arne Duncan had expressed support for gay unions.
The interview with ABC News' Robin Roberts was apparently hastily arranged as Mr Obama came under mounting pressure to clarify his position on the issue.
During the ABC interview, which airs later on Wednesday, Mr Obama pointed to his administration's commitment to increasing rights for gay citizens.
He also cited the repeal of the military's 'don't ask, don't tell' policy and said his administration had dropped support for the Defense of Marriage Act.
"I've stood on the side of broader equality for the LGBT community. I hesitated on gay marriage in part because I thought civil unions would be sufficient," Mr Obama said.
"I was sensitive to the fact that for a lot of people, the word 'marriage' evokes very powerful traditions, religious beliefs.
"I have to tell you that over the course of several years as I have talked to friends and family and neighbours, 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," Obama said.
"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."
In 2010, Mr Obama said his views on the issue were "evolving", a stance that had frustrated gay rights supporters and donors.
His comments came a day after North Carolina approved a constitutional amendment effectively banning same-sex marriage or civil unions.
Before that vote, the Obama campaign had opposed the measure, which was passed with 61% in favour and 39% against.
While Mr Obama is the first US president to support gay marriage, correspondents said the president's views on gay marriage were likely to upset some voters.
Some African-American voters oppose same-sex marriage on religious grounds.
