The next Archbishop of Canterbury has backed the ordination of women bishops, saying it is "time to finish the job" started with appointing women priests.
The Rt Rev Justin Welby also told the Church of England general synod he would ensure provisions for opponents were "carried out faithfully".
The synod is voting on proposed legislation. Bishops and clergy are expected to achieve the necessary two-thirds majorities in favour.
But the lay members' vote may be tight.
Justin Welby, currently Bishop of Durham, told the synod he was "deeply committed" to seeing that concessions to opponents of women's ordination were carried out.
He said the Church needed to show it could "Manage diversity of view without division - diversity in amity, not diversity in enmity."
"We cannot get trapped into believing this is a zero sum decision where one person's gain must be another's loss," he added.
Twenty years after the introduction of women priests, the issue continues to divide traditionalists - among those on the Church's evangelical and Anglo-catholic wings - from reformers.
Remaining divisions in the synod centre on whether concessions - under which parishes objecting to women bishops can request to be placed under a stand-in male bishop - go far enough, or too far.
If backed by the synod, the legislation would then make its way through Parliament and could lead to the first women bishops being ordained by 2014.
The Bishop of Liverpool, the Right Reverend James Jones, a noted evangelical, said he had changed his mind on the issue. "I now believe that for the mission of God to the people of England it is right for women to take up their place in this House of Bishops sitting before you now," he told the synod.
Canon Rosie Harper, vicar of Great Missenden, Buckinghamshire, said earlier in the debate: "If the proposed legislation passes there will be those who say that the assurances they have been given are too weak - but those assurances will be firmly in place.
"If the proposed legislation fails, the consequences I believe are far more severe."
She went on: "Firstly, as a Church for the whole country we will be seen to have failed to do what is right and honourable; a Church with lower moral standards than the rest of society risks its right to comment on other issues.
"Secondly, it will inevitably be seen as the act of a dying Church more wedded to the past than committed to hope for the future."
But Canon Simon Killwick, vicar of Christ Church, Moss Side and leader of the Catholic group in the synod, insisted that the measure before it was "not fit for purpose".
He said that the compromise wording on provision for opponents of women bishops was "no compromise at all, because it has united against it the whole spectrum of traditionalists."
And the Reverend Rod Thomas, vicar of St Matthew's Elburton, Plymouth and leader of the Evangelical group Reform, said the measure was forcing members of the Church "to accept something that we do not believe the Bible teaches".
"That is profoundly un-Anglican to force people into this position," he said.
The Archbishop of Canterbury, Rowan Williams, told the synod that "a no vote will not do anything positive" for the church of England.
He asked members to act on the "reasonable probability" that allowing women bishops was the right move and to seize this 'potentially liberating moment for us all'.
Women now make up about a third of all clergy in the Church of England.
The current process of formulating legislation to allow their ordination as bishops began in 2000.
The arrangements for instances when a female bishop is appointed but traditionalist parishes reject her authority have proved a stumbling block to its approval.
Under the plans, a woman bishop would delegate to a stand-in male bishop, but traditionalists want to be sure he would be sympathetic to their views - and not a supporter of women bishops - and not be getting his authority from the woman bishop.
A vote by the synod was adjourned in July after supporters of women bishops objected to a concession they felt went too far, by suggesting stand-in male bishops exercise their ministry in accordance with the parishes' "theological convictions".
The legislation has since been reworded to say the male bishop should be selected in a manner that "respects" the reasons why the parish asked for him.
Approval requires two-thirds majorities in each of the synod's three houses: bishops, clergy and laity.
If the measure is approved, the legislation will go to Parliament before receiving royal assent. The synod must then debate a Code of Practice on how the law will be carried out.
If it is defeated, the legislative process will need to start again and another vote would not take place before 2019.
Some Anglo-Catholics and conservative evangelicals continue to reject a deal, and a coalition of traditionalists, evangelicals and Catholics within the Church has sent a booklet to all 468 members of the synod arguing the draft measure falls short of what they need.
In a letter to the Times newspaper on Friday, signed by 327 clergy from all but one of the Church's 44 dioceses, they said backing for the draft measure would "lead irrevocably to deep fractures appearing within the Church".
Meanwhile, more than 1,000 Church members, including bishops, clergy and senior laity, have signed an open letter - published in the Independent newspaper - urging the synod to vote in favour.