In what could be one of the most decisive interventions of his
leadership - even before he takes over as Archbishop - the Bishop of
Durham, the Rt Rev Justin Welby, will urge doubters to back the measure
in the name of unity.The vote at a special session of the Church's General Synod in London will be the first test of his authority as chosen successor to Dr Rowan Williams.
Although there is overwhelming support in the Church for women in the episcopate, the vote is expected to be on a knife-edge because it would take only a small number to deny the measure the two thirds majority it needs in all three parts of the Synod.
But Bishop Welby's vocal endorsement of the measure last week, moments after being announced as the next Archbishop, is being seen as a potential "game-changer".
He is understood to be spending much of this weekend drafting his speech, striking a balance between saying that it is time for the Church to move on and offering assurances to those with theological objections to women bishops that there will be proper "provision" for them.
Coming from the evangelical wing of the Church, while also an enthusiast for Roman Catholic forms of worship, he is respected within the very circles where theological doubts about women in leadership are strongest.
He said last week that he would "value and learn" from those who could not support his stance adding: "I want the church to be a place where we can disagree in love."
An online campaign called "Yes2Women Bishops" organised by the blogger "Church Mouse" has attracted large support in recent days.
But the scale of the challenge he faces was underlined yesterday when the leader of the Roman Catholic Church in England and Wales, the Archbishop of Westminster Vincent Nichols underlined his "concern" about what he described as "the very significant step" the Church of England is about to take.
Close attention will also focus on the Bishop of London, Richard Chartres, who is respected by many traditionalist Anglo-Catholics.
He has thus far attempted to maintain a level of neutrality of the issue by deliberately declining to ordain women priests while publicly speaking in support of their ministry.
There is speculation that he might urge opponents to abstain rather than vote against to avoid a split.
Although Bishop Welby is well known as a supporter of women in the episcopate, the timing of his elevation, which was delayed by several weeks, coming on the eve of the vote, could prove decisive.
"No one could have predicted the timing of that statement which will be ringing in the Synod's ears in the vote that we are now going on to," said Christina Rees, a member of the Archbishops' Council.
"It is extraordinary to have an Archbishop designate coming out with such confidence.
"It just felt that his confidence and his strong support will encourage some of the Synod members who maybe didn't know the best way forward or were concerned for some of their friends."
Archbishop Nichols said yesterday that a vote for women bishops would not "fundamentally alter" the dialogue and co-operation between the two churches.
But, in a signal that it could set back moves towards eventually reuniting the two, he added: "It will create an additional sense of an identity within the Church of England which is less approximate to the Catholic tradition.
"The dialogue will continue but this is a very significant step which the Church of England now stands about to take, it would seem."