Bishop Charles Bennison Jr. of Philadelphia acknowledged the step will be divisive, The Philadelphia Inquirer reported Thursday.
"For some people, it's going to be troubling. For others, it's going to be thrilling," Bennison said.
The liturgy to be presented to delegates blesses gay relationships. Advocates say the couples will not be married, although the language is similar to that used in the wedding ceremony.
The role of homosexuals in the church has been a contentious one for two decades. In 2004, Gene Robinson, an openly gay Episcopal priest in a committed relationship, became bishop of New Hampshire. Some conservative parishes and dioceses have left the U.S. church, affiliating instead with others who share their views in Africa and South America.
The convention runs through next Thursday.