Labour Party leader Jacinda Ardern will be in Christchurch on Sunday and make her own announcements regarding the earthquake rebuild projects.
English said he had been advised the shortfall after today's funding announcement was about $80m.
"That will largely be a matter for the council and looking at the way other stadiums have been funded. So that's often a combination of sponsorship or other forms of local funding. So that is a discussion that can now be entered into."
English said a stadium with a full roof would allow multi-use of the facility.
Greater Christchurch Regeneration spokeswoman Nicky Wagner said the timeframe talked about for the stadium build had been 2020, but that could be brought forward.
Today's announcement was a party one - meaning the funding would be made available if National is re-elected.