Christchurch mayor Lianne Dalziel says if there is to be any certainty on the Christ Church Cathedral's future, the Anglican Church's synod must vote in favour of restoration.
At Thursday's city council meeting Dalziel said there was only one decision the synod could make in September that would provide that certainty - voting for restoration.
"If the synod make the decision not to restore the Cathedral, we will have uncertainty for years and that is something I don't think the city can tolerate.
"I think there is only one decision that actually takes us forward as a city. And there is no other decision that will lead to anything else other than uncertainty and legal wrangles for years."
Bishop Victoria Matthews announced last month the synod, a governing body made up of 225 parishioners and priests, would vote on whether to restore, or rebuild the earthquake-damaged building in September.
Dalziel said she was "blindsided" by that decision.
"I didn't know that was going to be coming out as a position. So I initiated a meeting with the Bishop because I felt we hadn't had a meeting since my re-election last year. And it is really important for the city to be fully engaged in what is an incredibly important part of our city."
Her comments came after Restore Christ Church Cathedral co-chairmen Mark Belton and Tim Preston spoke before councillors, asking them to take a stand.
Belton said it was important residents and city councillors read the Government-appointed working group report, released last month, which recommended the Cathedral be restored.
The report called for the reinstatement at an cost of about $105 million, to be funded by philanthropic and public donations, the insurance proceeds and support from central and local government.
He said if the synod voted for the Cathedral to be demolished and rebuilt, it would likely go to court.
"It can't be a vote to take away the Cathedral and have it rebuilt. It can only be a vote to take the matter to court."
Preston asked councillors to think about whether they believed the state of the Cathedral was acceptable to the city.
"It's certainly not acceptable to me."
He encouraged them to look at attending the pre-synod meetings, which Dalziel said they would be interested in.
Dalziel said she had asked staff to urgently prepare a report on the working group's recommendations to give some sense of direction on what the city could promote or contribute.
She was expecting that report back within a "very short space of time".