In a letter on Monday to the White House, more than 50 gay rights and immigrant advocacy groups asked President Obama to put a hold on immigration cases involving Americans seeking legal residency visas for foreign-born spouses of the same sex, until the Supreme Court issues a significant ruling on gay marriage next year. The gay and immigration organizations are joining forces on the marriage issue, hoping to capitalize on political momentum they gained from the elections, when gay, Latino and immigrant voters turned out overwhelmingly in support of Mr. Obama. The groups urged the president to “hold in abeyance” cases currently under consideration by federal immigration authorities of United States citizens who are seeking permanent resident visas, known as green cards, for immigrants of the same sex they legally married. The Supreme Court ruling is expected in June. Under the federal Defense of Marriage Act, which Congress passed in 1996, a same-sex marriage cannot be a valid basis for federal benefits, including immigration documents. For an American who marries an immigrant of the opposite sex, obtaining a green card for the spouse is generally a routine and relatively fast procedure.