The Church of England is set to vote on whether women should be allowed to enter its top ranks as bishops.
The Church's national assembly, known as the General Synod, is meeting in York, northern England, where it will debate the issue ahead of a vote on Monday.
Justin Welby, spiritual leader of the world's 80 million Anglicans, said the general public would find it "almost incomprehensible" should the General Synod fail to support the move.
The vote comes two years after similar legislation failed to reach a two-thirds majority among the General Synod's lay members, despite approval from bishops and clergy.
"I think we look ridiculous. God has been calling us on this road for a long time and we need to get on with it.
The long-running debate pits reformers, keen to project a more modern and egalitarian image of the church as it struggles with falling congregations in many increasingly secular countries, against a minority of conservatives who see the change as contradicting the Bible.
Local media have said Welby is planning to push through the legislation even if it is rejected by the General Synod.
But, asked if he could ignore the Synod and impose women bishops on the church anyway, Welby said: "Absolutely not."
"What happens if we lose the vote is a matter for the House of Bishops," he said, referring to one of three parts of the General Synod. "I can't dictate it."
The issue of female clergy has divided Anglicanism globally.
Women serve as bishops in the United States, Australia, Canada and New Zealand but Anglican churches in many developing countries do not even ordain them as priests.
"I think we look ridiculous. God has been calling us on this road for a long time and we need to get on with it," Meg Gilley, a female clergy member at the Durham Diocese in England, told Al Jazeera.
The Church approved the ordination of women priests in 1992, but delayed making them bishops because of opposition within its previously all-male clergy.
Traditionalists within the church, however, opposed the move to ordain female bishops, claiming that their argument is based on theology.
"In principle the bible teaches that men and women were created equal but different," Susie Leafe, director of Reform, told Al Jazeera. "God has different roles for us in the church in the chrch family, and so for me bishop represents a role that is designed for man."
The Church of England is part of the Anglican Communion, which has the largest Christian denomination in Britain and a presence in more than 160 countries.