DAR ES SALAAM, Tanzania — The Archbishop of Canterbury flies into the biggest Anglican crisis since the Reformation today without even knowing whether his fellow church leaders will sit in the same room together.

Dr. Rowan Williams will arrive at a meeting of bishops in Tanzania, East Africa, with compromise proposals that he hopes can avert a schism by bridging the abyss between the factions warring over homosexuality. But when he reaches the White Sands conference center in Dar Es Salaam, he will find the primates, the leaders of the worldwide communion’s 38 self-governing provinces, more polarized than ever. Even before his plane touches down, the event has become mired in unprecedented levels of politicking that have challenged his moral authority as “first among equals.”

To the consternation of officials, the conservative primates have set up their own headquarters in the neighboring Beachcomber Hotel, at which they will determine their collective strategy, and they are threatening to snub the presiding bishop, Katharine Jefferts Schori, who is the liberal leader of the Episcopal Church — the American branch of Anglicanism.

A number of them are furious that Dr. Williams did not consult before inviting Presiding Bishop Schori, who is a supporter of gay clergy and same-sex blessings and who was elected as Anglicanism’s first woman primate last summer.

If they refuse to deal with her, aides fear that she may leave the meeting, derailing Dr. William’s peace proposals before they start. Alternatively, the archbishop could be reduced to shuttling between rival groups in different rooms, an extraordinary prospect for the church.

“We just don’t know how any of this is going to work out at this stage,” one insider said. “It could become very awkward indeed.”

The conservative Global South group will finalize its position at a two-day meeting starting today, the outcome of which could prove as critical as the official five-day primates’ meeting beginning on Thursday.

Drawn primarily from Africa and Asia, Global South consists of about 20 primates representing well over half the worldwide church, led by the controversial primate of Nigeria, Archbishop Peter Akinola.

Anglican officials are hoping that divisions between hard-liners and moderates will surface within this group over the next two days, allowing Dr. Williams to appeal to the middle ground. “Much will depend on whose voices dominate the Global South caucus,” one said.

But a leading conservative, the primate of Central Africa, Archbishop Bernard Malango, said many of his colleagues would find it “very difficult” to work with Presiding Bishop Schori. He added that the presence of the Archbishop of York, Dr. John Sentamu, for the first time was also problematic because it had been decided without full consultation. In a warning to Dr. Williams, he said, “If people have come in a spirit of give and take, that will happen. But if people have made up their minds to bring certain people here, then it will be difficult. I don’t want to see the Church damaged, but if some groupings, especially those who are not faithful to the scriptures, decide to do their own thing, then that puts me in a difficult situation.”

If Dr. Williams succeeds in persuading the primates to negotiate together, however, his problems are far from over. The main item on the agenda is the fate of the Episcopal Church, which brought the worldwide church to the brink of schism by consecrating Gene Robinson as Anglicanism’s first openly gay bishop in 2003.

The American church was asked to apologize for breaching official policy and to toe the majority line by imposing a moratorium on future consecrations of gay bishops and blessings of same-sex “marriages.” But it refused to do so at its general convention last summer.