PHILADELPHIA — Sixteen fractious years after it allowed the ordination of homosexuals, the Episcopal Church appears poised to adopt a blessing rite for same-sex couples wishing to wed.

If approved, as expected, at the church’s general convention starting today in Indianapolis, the liturgy would be the first such rite endorsed by a major U. S. denomination.

Advocates of the blessing — already written, down to the “We have gathered here today” and “I do” and the exchange of rings — stress that it is not a sacrament and would not confer “marriage” on the couple.

Episcopal Church law defines marriage as the union of man and woman, and there are no plans to change that this year.

The 2009 convention had encouraged bishops in states allowing same-sex marriage, currently six, plus the District of Columbia, to “provide generous pastoral response” to gay and lesbian members. It also authorized creation of the rite now under consideration.

Its passage would be a major advance for gay people within the 2 million-member denomination, said Bishop Charles Bennison Jr. of the Diocese of Pennsylvania.

He serves on the legislative committee that will present the measure to the 300-member House of Bishops and the 800 laity and clergy who make up the House of Deputies. If the same-sex blessing is to pass, both houses must approve it.

The measure seems to have broad support in the House of Deputies, Bennison said. Some moderate bishops, he added, fear that it could divide their dioceses. A hearing on the blessing is set for Saturday, but a vote is not yet scheduled.