After years of debate, the Anglican Church of Canada is expected to vote today on gay marriage. However there is strong opposition from some bishops and the measure is not certain to get the two-thirds majority it needs to pass.

The Church's General Synod is currently meeting in Ontario.

If passed, the resolution will change the definition of marriage in canon law.

The words "union of man and woman" and "husband and wife" would be replaced by the word "partner", meaning that clergy would be able to carry out legal same-sex marriages in Anglican churches in the province if authorised by the diocesan bishop.

The debate today is the first of two readings. If passed, the second will not be until 2019.

The Canadian Church already carries out blessings for same-sex civil partnerships.

Indigenous bishops in particular are resentful at what they regard as the imposition of a Western cultural agenda.

An Anglican commission set up in 2013 in Canada to look at drafting a motion on the issue reported: "The experience of same-sex committed partnerships in our midst, clearly manifesting God's blessing and the fruit of the Spirit, are a powerful indication that God's view of marriage may be more inclusive than ours."

Michelle Bull, an ordinand who is one of the most outspoken advocates of the move, told Anglican Journal that if "someone asks me to marry them and they're gay, and the Anglican church says that I can't, that's going to rip me to pieces."

The vote comes weeks after 24 members of the Anglican Bishops in Dialogue group met in Accra, Ghana, to discuss resolving differences and conflicts such as those around sexuality.

Several Canadian bishops were present at the meeting, including Jane Alexander of Edmonton, Michael Bird of Niagara and Michael Ingham, retired bishop of New Westminster.

Archbishop Fred Hiltz, Primate of the Anglican Church of Canada, also attended briefly along wth US Presiding Bishop Michael Curry.

Hiltz spoke at the meeting about the gay marriage vote.

"I plunked it right on the table: the marriage canon," he said according to Anglican News. "Some of them, I think, were actually relieved that the elephant in the room was no longer the elephant in the room, that I actually had put it right on the table."

He said it was no longer possible for other provinces to avoid the issue.

With the more formal "Instruments of Communion" frequently jammed by very public disagreements over human sexuality, it is in the informal bodies, like diocesan partnerships and the consultation of bishops, that a lot of important work gets done, he argued.

The Bishops in Dialogue group is among those groups outside the formal structures "that really speak to the life, the vitality, the compassion, courage, the pastoral and prophetic witness of the communion," he said.

Next year the consultation will be in Kenya, a leading supporter of the conservative Global Anglican Futures Conference, or Gafcon.

Hiltz said it was "significant" that Kenya is hosting the next consultation of the Bishops in Dialogue group.