The United Methodist Church’s top legislative assembly convenes Sunday for a high-stakes, three-day meeting likely to determine whether America’s second-largest Protestant denomination will fracture due to divisions over same-sex marriage and the ordination of gay clergy.

While other mainline Protestant denominations — such as the Episcopal and Presbyterian (U.S.A.) churches — have embraced gay-friendly practices, the Methodist church still bans them, even though acts of defiance by pro-LGBT clergy have multiplied and talk of a possible breakup of the church has intensified.

At the church’s General Conference in St. Louis, 864 delegates — split between lay people and clergy — are expected to consider several plans for the church’s future. Methodist leaders said they expect a wave of departures from the church regardless of the decision.

“I don’t think there’s any plan where there won’t be some division, and some people will leave,” said David Watson, a dean and professor at United Theological Seminary in Dayton, Ohio, who will be attending the conference.

Formed in a merger in 1968, the United Methodist Church claims about 12.6 million members worldwide, including nearly 7 million in the United States. In size, it trails only the Southern Baptist Convention among U.S. Protestant denominations.

The church technically forbids same-sex marriage and gays serving in the ministry, but enforcement has been inconsistent. Clergy who support LGBT rights have been increasingly defiant, conducting same-sex marriages or coming out as gay or lesbian from the pulpit.

At the heart of the ideological conflict is an official UMC policy, dating from 1972, asserting that “the practice of homosexuality is incompatible with Christian teaching.”

One of the proposed plans, endorsed by the UMC’s Council of Bishops, would remove that language from the church’s law book and leave decisions about same-sex marriage and ordination of LGBT clergy up to regional bodies. This proposal, called the One Church Plan, would open up many options for those who support the LGBT-inclusive practices, but it would not compel individual churches or clergy to engage in those practices.

The proposed Traditional Plan would affirm the bans on same-sex marriage and the ordination of “self-avowed practicing homosexuals.” The plan would strengthen enforcement of those bans, and set up procedures for churches and regional bodies to leave the UMC if they could not abide by those rules.

A third option would create three branches of the church reflecting the different approaches to LGBT issues. One branch would maintain the current bans, another would expect all its clergy and regional groups to support full LGBT inclusion, and the third would neither forbid nor require the inclusive practices. This plan would take several years longer to implement than the others.

Those three plans were developed over 17 months of deliberations by a Methodist committee that was formed after conflict over LGBT policies boiled over at a General Conference in 2016. In accordance with Methodists’ long tradition of democratic policy-making, delegates in St. Louis will be free to revise any of those plans, or consider some alternative.

In December, the Council of Bishops issued a pastoral letter expressing remorse that the buildup to the St. Louis conference has been hurtful to many LGBT people.

“Demeaning and dehumanizing comments and attacks on LGBTQ persons in conversations related to the upcoming February Conference are a great tragedy and do violence to hearts, minds, and spirits,” the letter said. “We commit ourselves to helping people who disagree with each other to have conversations that include, honor, and respect people with different convictions.”