Developer Henderson proposes to alter the scheme given approval in 2009 and the Cabinet on July 10 is due to decide on whether to let the application be made.
Henderson want to cut out any affordable housing and shelve a new bus station, attracting much controversy.
But councillors at the Town Forum voted that there should be another public display of the new proposals and a debate at a full meeting of Council. There was cross-party support for a resolution by Cllr Martin Tod.
Cllr Tod said: “I’m concerned we could end up having a cabinet meeting without the public having had the chance to consider the final proposals.”
The council has responded by announcing the new plans will be on display on July 12-13 at a venue to be confirmed.
There was a two-day public consultation in March but it was arranged at short notice with many interested people unaware.
City councillor Kim Gottlieb has recently started a campaign Winchester Deserves Better to reduce the size of the £150 million scheme. The main building will be six or seven storeys tall.
Corporate director Steve Tilbury said the Cabinet decision was the council acting only as a landowner and will not affect the council’s later planning decision. “they are two separate decision,” he said. There will be public consultation as part of the planning application.
Cllr Richard Sanders said July 10 was a crucial day. He said if Cabinet give permission to Henderson to submit a planning application they give up a position of strength. “The council has absolute discretion to say you cannot do that. If Henderson say we don’t want a bus station, we can say we do want a bus station. They don’t want affordable housing. We do want affordable housing. We can tell Henderson to poke it.”
Silver Hill will next be discussed at the overview of scrutiny committee on July 7, at Cabinet on July 10 and then full Council on July 16.