A potential third option for the Christchurch Cathedral is not getting a wave of favour from the Prime Minister.

The building has stood derelict since the 2011 earthquakes, and the Anglican synod is set to finally vote on what happens to it next month.

The options initially were to either demolish the cathedral and build a new one or to fix it. However now the synod has indicated it could be gifted to the Government, in which case it would become a public building.

When asked whether he'd be interested in the third option, Bill English said he's not sure what it would entail.

"While it's a brand new option and we don't want to get in the way of the synod process, so we would have to consider what they think they mean by that."

The Labour candidate for Christchurch Central said the cathedral would be a massive liability if it is separated from insurance money.

Dr Duncan Webb said the first two options guarantee the Church a cathedral, but that is not certain with the third.

"The church needs a cathedral. It needs a place for worship and for its community and it absolutely needs some or all of those insurance money to do that. The transitional cathedral is just that, it won't last forever, it's not consented forever."

He said the first two options make more sense.

"It's almost a walk away, not our problem option and I'm not sure that works because it is the Anglican cathedral."