PROVIDENCE — Legislation to allow gay marriage in Rhode Island is headed for a vote in the state House of Representatives after being unanimously endorsed Tuesday by a legislative committee.

The full House is expected to debate and vote on same-sex marriage Thursday. Though gay marriage bills have been introduced for years, it will be the first time either chamber of the General Assembly will vote on the matter.

The bill was endorsed Tuesday by the House Judiciary Committee. The panel’s chairwoman, state Representative Edith Ajello, a Providence Democrat, called it ‘‘truly a historic moment.’’

‘‘Many of us have been waiting for this for a number of years,’’ Ajello said.

The legislation is expected to pass the House but its prospects in the Senate are far more difficult to forecast. That is where gay marriage foes are hoping to defeat the bill.

Governor Lincoln Chafee hailed Tuesday’s committee vote as ‘another significant step forward toward marriage equality.’

‘‘The Senate is still up for grabs,’’ said Christopher Plante, director of the state chapter of the National Institute for Marriage, which opposes same-sex marriage.

Senate President Teresa Paiva Weed is a gay marriage opponent and said last week that she could not support the legislation as written. But she has said she would allow the Senate Judiciary Committee to review and vote on the bill if it passes the House.

House Speaker Gordon Fox had called for a vote in his chamber on gay marriage by the end of January. Fox, who is gay, dropped similar legislation two years ago after it became apparent the legislation would not pass the Senate. Lawmakers instead approved civil unions for same-sex couples.

Governor Lincoln Chafee, a gay marriage supporter, hailed Tuesday’s committee vote as ‘‘another significant step forward toward marriage equality.’’