Bills have been introduced in Congress to treat same-sex partners like heterosexual spouses for the purposes of immigration but are likely to face a strong fight, both from equality opponents and anti-immigration groups. The 1996 Defense of Marriage Act prevents immigration officials from recognizing gay marriages, even from states where they are now legal.

Proponents see the issue as a basic rights question, and Steve Ralls, a spokesman for Immigration Equality, said he believes the best chance for the legislation is as part of a larger immigration bill.

But other immigration advocates want to keep the issues separate, fearful of bogging down an already tough fight. Kevin Appleby, migration policy director for U.S. Conference of Catholic Bishops, said the push for same-sex partners in immigration is about getting recognition in federal law for equal marriage -- which he opposes.