Fifty percent of those surveyed agreed with federal judges who have found recently that the Equal Protection clause requires that gay and lesbian people be allowed to tie the knot. Another 43 percent said it does not, while the rest were unsure.
In states that continue to ban same-sex marriage, 45 percent said it has constitutional protection and 48 percent disagreed. But even in those states, half said same-sex couples should be able to marry.
In the country as a whole, 56 percent support same-sex marriage and 38 percent oppose it. While public support has generally risen since Massachusetts became the first state where same-sex couples could marry legally 10 years ago, it has dipped slightly since last year, with the largest declines among those older than 50.
In the youngest group, those 18 to 29, more than 75 percent believe same-sex marriage should be legal.
Since the U.S. Supreme Court ruled last year that the federal Defense of Marriage Act is unconstitutional, bans have been challenged in many states. In Pennsylvania and Oregon, state officials have declined to appeal judges' rulings overturning the bans, while other cases are on hold pending appeal or have not yet been decided.