The Presbyterian Church (U.S.A.) narrowly rejected a proposal to change its definition of marriage from the union of a man and a woman to two people.
The Presbyterian General Assembly voted 338-308 against the measure near the end of its national meeting Friday in Pittsburgh.
The plan to revise the definition was proposed a year after the denomination struck down barriers to ordaining people in same-sex relationships. Several theologically conservative churches have either left the denomination or moved away from its leadership as a result of that decision.
Gay marriage advocates have said a revision was needed now that six states and the District of Columbia have legalized same-sex marriage.
Only one major U.S. Protestant group has endorsed same-sex marriage outright. That's the United Church of Christ.