The Church of England is to take the historic step of voting on whether to give final approval to legislation introducing the first female bishops.
The General Synod, the Church's national assembly, will take a series of votes after a debate on whether to allow the legislation to clear its final hurdle before going to Parliament for approval.
The vote is billed as the most significant step in 20 years taken by the General Synod, a 470-strong body made up of bishops, clergy and laity, since it first backed the introduction of women priests. If given approval, the legislation will go to the Houses of Parliament before receiving Royal Assent, paving the way for the first women bishops in 2014.
A vote in favour of approval would usher in not only women bishops but the prospect of future female Archbishops of Canterbury or York, the two most senior posts in the Church of England. But the legislation needs a two-thirds majority in all three houses of the General Synod - bishops, clergy and laity - in order to gain final approval.
Commentators have said they believe the legislation will clear the houses of bishops and clergy with the necessary majority but the vote amongst lay members of the General Synod is thought to be close.
The first vote will be on whether to give final approval to the legislation with a second vote taken on a draft amending canon, a legal mechanism that will enable the legislation to become law. A third vote will be taken on whether to back a petition for Royal Assent.
The vote comes after years of torturous negotiations on how best to introduce women bishops within the Church of England amid opposition from traditionalists including some Anglo-Catholics and conservative evangelicals.
Under the legislation, a woman bishop would delegate to a stand-in male bishop to minister to parishes which rejected her authority, using a code of practice for guidance.
The legislation has been backed by 42 out of the 44 Church of England dioceses.
But traditionalists have attacked the arrangements in the legislation as inadequate, while some pro-women campaigners have complained that the concessions have been too generous to objectors. Currently 944 out of 12,792 parishes in the Church of England refuse to have a woman vicar.