Arne Duncan in The Guardian (U.K.)

On Civil Rights: Same-sex couples should be legally allowed to marry

Duncan's endorsement comes after the vice-president, Joe Biden, became the highest-ranking government official to back same-sex marriage on Sunday, telling Meet the Press he was "absolutely comfortable" with the issue. Obama has appeared reluctant to take up the issue in an election year but has said his views are "evolving" on the subject.

The comments by Biden and Duncan opened up speculation that the White House is moving towards a new position of support for gay marriage, beyond its already stated backing for civil unions. But Obama's main political strategist played down the prospect of an imminent shift.