NEW YORK — America’s largest mainline Protestant denomination is on a path toward likely breakup over differences on same-sex marriage and ordination of LGBT pastors.

The differences have simmered for years among the United Methodists and came to a head in February at a conference in St. Louis where delegates voted 438-384 for a proposal called the Traditional Plan, which strengthens bans on LGBT-inclusive practices. A majority of U.S.-based delegates opposed that plan and favored LGBT-friendly options, but they were outvoted by U.S. conservatives and most of the delegates from Africa and the Philippines.

Many believe the vote will prompt an exodus from the church by liberal congregations that are already expressing their dissatisfaction over the move.

Some pastors have vowed to defy the strict rules and continue to allow gay weddings in Methodist churches. Churches are withholding dues payments to the main office in protest, and the UMC’s receipts were down 20 percent in March, according to financial reports posted online.