A Church of England bishop has warned that hundreds of traditionalist clergy may leave for the Roman Catholic Church if women are ordained as bishops.
Women priests were first ordained more than 10 years ago
The Church's synod is debating the issue in York on Monday.
Opponents have renewed their demand for a separate division of the Church from which women bishops would be barred.
The Bishop of Ebbsfleet told the Sunday Times if women were ordained the Church would not have "a united episcopate" and he "would have to leave".
Around 400 Anglican clergy became Roman Catholics when women were first ordained as priests in 1994.
Women now make up half of those training as Anglican clergy.
But for traditionalists, Jesus' choice only of men to be his disciples, and the 2,000-year-old unbroken chain of male bishops dating from the early Church rule women out of the role.
The Bishop of Ebbsfleet, Andrew Burnham, looks after parishes who have rejected women priests .
Bishop Burnham told the Sunday Times women could not be bishops, and that he would consider becoming a Roman Catholic were they to be ordained.
"A woman bishop wouldn't be a bishop because a bishop is someone whose ministry is acceptable through the ages to all other bishops," he said.
"A Church of England with women bishops would no longer have a united episcopate.
"Bishops would no longer be what they say they are. I would have to leave."
The Bishop of Fulham, John Broadhurst, told the paper there would be an exodus unless a separate area of the Church was created, from which women were barred.
"The introduction of women bishops without proper provision [for opponents] would be intolerable," the paper quoted him as saying.
Last week a group of bishops warned that proceeding with the plans would endanger the unity of the church.
The July Sessions of the synod, which sits twice a year, began in York on Friday.
On Saturday, members voted 293 to one against a bill that would legalise euthanasia.
The Assisted Dying for the Terminally Ill Bill was introduced in the House of Lords last year.
Addressing the synod, the Archbishop of Canterbury, Dr Rowan Williams, reaffirmed his stance against euthanasia, arguing it was aimed at cost cutting in the health service.
"In a climate where the pressure is all towards a functionalised, reduced style of healthcare provision, this [assisted dying] must be a very, very tempting option to save money and resources," he said.