WASHINGTON - Same-sex couples would be allowed to marry in the nation’s capital under a bill introduced yesterday by a District of Columbia councilman.

The bill was almost certain to pass and had been expected for some time. But whether it becomes law is more complicated because Congress gets to review D.C. legislation before it takes effect.

At least one Republican congressman has said he will work to have the bill defeated if it passes the D.C. council.

“Some fights are worth fighting for,’’ said US Representative Jason Chaffetz of Utah, who thinks Democrats in Congress would probably block any vote on D.C.’s measure. “This is one of them.’’

The city began in July recognizing same-sex marriages performed elsewhere. Congress had a chance to act on that legislation, but it quietly passed earlier this year. D.C. Councilman David Catania introduced the new bill at a standing-room only council meeting. The independent and one of two openly gay council members said he hopes for a vote in December.

“There is no question that we are about to embark on an exciting journey here in the district,’’ he said. His bill specifically said religious leaders and institutions are not required to perform the marriages or rent their space for same-sex ceremonies.

If the bill becomes law, the city will follow Massachusetts, Connecticut, Iowa, and Vermont, which issue marriage licenses to same-sex couples. New Hampshire will begin issuing them in January.

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