MILWAUKEE — A growing number of pastors in the United Methodist Church say they're no longer willing to obey a church rule that prohibits them from officiating at same-sex marriages, despite the potential threat of being disciplined or dismissed from the church.

In some parts of the U.S., Methodist pastors have been marrying same-sex couples or conducting blessing ceremonies for same-sex unions for years with little fanfare and no backlash from the denomination. Calls to overturn the rule have become increasingly vocal in recent weeks, ratcheting up the pressure for the Methodist church to join other mainline Protestant denominations that have become more accepting of openly gay leaders.

While trials of pastors who conduct same-gender ceremonies have only occurred once every several years, the threat is indeed real: The Rev. Amy DeLong of Osceola in western Wisconsin faces a three-day trial starting Tuesday on two charges: violating a church prohibition on the ordination of "self-avowed practicing homosexuals" and marrying a lesbian couple.

She said she told her supervisors years ago that she was in a lesbian relationship.

While she avoided discussing her relationship in local church settings, she said her efforts to live halfway in the closet and halfway out took such a toll that she finally decided to break her silence. She agreed to marry a lesbian couple in the fall of 2009, and she didn't mince words when she reported it in a required ministerial report a few months later. Eventually the two church charges were filed against her.

"I would be lying if I said this process hasn't been difficult, but I also feel called to break the silence and tell my own truth regardless of the consequences," said DeLong, 44.

The chances of getting the rule reversed within the Methodist church are far from certain, however. Rule changes must be approved by delegates at the church's General Conference, held every four years. Because a growing number of delegates come from Africa, the Philippines and other theologically conservative regions, voting patterns reflect strong resistance to change.

That hasn't stopped Methodist clergy in the U.S. from raising the stakes. Hundreds of pastors from states including Illinois, Minnesota and New York have signed statements in recent weeks asserting their willingness to defy the rule.

Those who do so could be charged with violating denominational law and forced to face a church trial. Penalties could include defrocking or suspension from the ministry.

Theologically conservative Methodists believe the Bible bars same-sex relationships and have been advocating for years to keep the prohibition against same-gender marriage in the Methodist's Book of Discipline.

An executive with an advocacy group for conservative mainline Protestants said he didn't expect the provision would be changed anytime soon. Mark Tooley, the president of The Institute on Religion and Democracy, said it would either have to be overturned by a vote of the whole worldwide delegation, or the delegation would have to allow the U.S. delegation to set rules specifically for itself. Neither option has historically gained much traction, he said.