A majority of the church's governing General Synod is ready to say yes, but that doesn't mean it's all wrapped up. The vote needs a two-thirds majority in order to be approved, and an unlikely coalition of advocates and opponents of female bishops may have enough strength to derail the motion. Some voices on both sides argue that the church's compromise asks them to concede too much.
While opening the way for female bishops, the proposal before the General Synod also commits the church, when it assigns priests and bishops, to "respect" the position of parishes that oppose them—without defining what respect means in practical terms.
Archbishop of Canterbury Rowan Williams, the church's outgoing leader, has been campaigning for approval with a touch of exasperation: "Enough waiting," he said.
If the vote falls short of the two-thirds majority, the General Synod would have to start all over. Church officials say it could take five years to prepare new legislation and complete all the steps leading to a final vote.
"The tough question for those who are still undecided," said Williams, "is whether delay would produce anything better.
There have even been calls, unusual in a church, to go the way of the world.
Peter Broadbent, bishop of Willesden in London, has called for a "yes" vote so that the church does not "look completely stupid in the eyes of society."
Supporters of the compromise are hopeful.
"Very, very few people are happy with it, but the vast majority now are going to go for it," said Sally Barnes of Women and the Church, which campaigns for female bishops. The vote may turn on how many opponents can be persuaded to abstain, she said Monday.
It has been 36 years since the General Synod declared it had no fundamental objection to ordaining women as priests, and 18 years since the first women were ordained. Meanwhile, sister churches of the Anglican Communion in Australia, New Zealand, Southern Africa and the United States already have women serving as bishops.
Tony Baldry, who speaks for the Church of England in the House of Commons, has said he would "find it impossible to explain to Parliamentary colleagues how a measure that commanded the support of 42 out of 44 dioceses in England failed to be approved by General Synod."
Many supporters of female bishops are nonetheless calling for a no vote, saying the latest attempt at compromise is another imperfect effort to bridge fundamental differences of principle.
A determined minority of hardcore opponents wants not merely to be subject exclusively to male bishops, but only those who refuse to ordain women. Jesus called 12 disciples, every one of them a man, the opponents argue.
Resentment of women priests is among the issues which has driven dozen of priests and more than a thousand parishioners to join the Ordinariate of Our Lady of Walshingham. It was created last year by Pope Benedict XVI as a sort of halfway house where Anglicans convert to Catholicism, safe from female priests, but may keep traditions including the Book of Common Prayer.
For Williams, Tuesday's vote is the last chance to resolve the issue before he steps down at the end of December.
For his successor, Bishop Justin Welby, it's the first chance to exert his authority in support of the compromise, which he emphatically endorsed on Nov. 11 after being chosen to lead the church.
"I want the church to be a place where we can disagree in love, respecting each other deeply as those who belong to Christ," Welby said.