Almost exactly two decades after it narrowly voted to allow females to join the ranks of its clergy, the Church of England is again at loggerheads over the role of women within its midst.

Tomorrow, after years of bitter debate, the General Synod will hold a crunch vote on whether to accept female bishops. As the final battle lines are drawn on either side, more than 1,000 members of the clergy and senior laity have put their names to a letter in The Independent urging the Synod to back what would be a historic move. Both the outgoing Archbishop of Canterbury, Dr Rowan Williams, and his successor, the Rt Rev Justin Welby, have already added their weight to the Yes campaign, along with the Archbishop of York, Dr John Sentamu.

Voting is thought to be tipping in their favour, paving the way for the first women to be ordained to the episcopate by January 2014. Candidates include June Osborne, the Dean of Salisbury Cathedral, Vivienne Faull, Dean of York Minister and Jane Hedges, Canon Steward of Westminster Abbey.

But traditionalists who oppose the move have lobbied ahead of the ballot in London, which must receive two-thirds support among bishops, clergy and lay members to become law. A defeat would be a big early blow to the authority of the incoming Archbishop, and cast a cloud over Dr Williams' departure after a decade in the role.

The "anti" camp has already forced concessions from the liberal majority, which mean that those who wish to avoid a female ministry will be allowed to do so.

Last week, 325 traditionalist clergy signed an open letter warning that allowing women bishops would "severely prejudice" their ministries and lead "irrevocably to deep fractures appearing within the Church". But in a letter to The Independent, published today, the Rev Dr Miranda Threlfall-Holmes, vicar of Belmont and Pittington, in the Diocese of Durham, urged the Synod to end decades of bitter wrangling over equality in the Anglican ministry.

"Just as the Churches have repented of our historic anti-Semitism and endorsement of slavery, so we believe that we must now show clearly that we no longer believe women to be inferior to men," the letter says.

The letter was backed by hundreds of church leaders, including five Bishops, ordinary members of the clergy and senior lay figures.

Dr Threlfall-Holmes said that her congregation had yesterday prayed for "the spirit of wisdom in the synod's deliberations".

Rose Hudson-Wilkin: Faith without compromise

Born in Montego Bay, Jamaica, the 51-year-old has been widely tipped to become the first female Church of England bishop. Charismatic and articulate with an engaging Caribbean lilt, she has spoken out against compromising with those traditionalists who would seek to bypass her ministry.