The Friends of Harris Park (FOHP) want the council to consider buying the run-down Victorian complex from wealthy businessman Yousuf Bhailok and preserve it for the city.
In a letter to former Preston Mayor Coun David Borrow, the group says the council should include it on the list of projects it is considering for an application for Levelling Up money.
"There are several ways in which the site could be re-purposed and turned into a self-supporting project," says the letter from Prema Taylor, one of the campaign organisers.
"If you were willing, we could discuss details which will demonstrate that this is not just wishful thinking, but a serious attempt to balance the need for progress and income with preservation of local history."
Plans by the Bhailok family to redevelop the site by renovating the historic buildings - many of them having Listed status - and also erecting 23 new homes on the former cricket field at the rear were thrown out by the city council almost a year ago.
The request from the Friends of Harris Park comes as a new planning application was submitted to the Town Hall this week asking for Listed Building Consent to repair the damage caused by years of neglect.
Dry rot and water ingress have caused major problems in all the buildings on the site and the application by Eden Grove Investment Properties Ltd - a company owned by the Bhailok family - is seeking to carry out urgent work to halt the decline of the properties.
A report to the planning department says the repairs are "essential" to prevent further damage by the weather.
"The roof repair work would drastically improve the condition of the buildings as well as preventing any further damage through water ingress/rot," says the report.
"The proposed work consists of essential and time-sensitive maintenance works necessary to safeguard historic buildings and prevent further damage.
"The work would be undertaken in a sensitive manner using appropriate like-for-like materials and avoiding unnecessary damage to historic fabric.
"The effects of this work will therefore be significantly beneficial and will preserve and enhance the significance of these assets."
In the letter to Coun Borrow, Mrs Taylor says: "We have a respectful working relationship with the private owner of Harris Park, who has indicated that he would be willing to sell the site so it may be restored and returned to use for the benefit of the community.
"We believe it is vitally important to preserve all viable remnants of Preston's heritage and history.
"The commitment and strength of feeling of the local community has been clearly demonstrated by the generous contributions of funds to facilitate professional assistance for the opposition to the planning application."
Mrs Taylor told the Lancashire Post: "The whole Harris Park campaign has evolved gradually over the last months. At the end of the day FOHP just want the best outcome for Harris Park.
"When the campaign started there were a lot of very bad feelings, insinuations and accusations flying around. I think as we have gone along the spirit of cooperation has seeped in, and all we want is a solution that is satisfactory to all parties involved."
The Friends of Harris Park group was set up in May 2020 following an avalanche of objections to the housing plans on the historic site.
More than 200 local people objected, along with Historic England, the Victorian Society, Sport England and Save Britain's Heritage, which said the redevelopment “threatens to destroy the integrity and unique significance of Harris Park, and conflicts with its status as a listed Park and Garden and conservation area.”
The Harris Orphanage was opened in 1888 and was closed as a children's home in 1982, having cared for more than 2,200 boys and girls during its 94 years.
Preston Polytechnic - later to become the University of Central Lancashire - took over the premises as an education hub and eventually sold it to Yousuf Bhailok in 2006 for around £6m.
He had the intention of turning it into an exclusive “village green-style” housing complex for members of his family.
But following a long-running planning row he offered to sell the site to the council for £6.5m - money which the Labour-run authority could not afford.
Mrs Taylor added: "We believe it is vitally important to take steps to preserve this unique piece of Preston's history which has the capacity to be developed sympathetically, restored to community use, brought to international renown, generate self-sustaining income, bring the past back to life for our children and teach them the importance of philanthropy alongside material success.
"Apart from two of the houses in Harris Park, the rest of the buildings are deteriorating rapidly and will reach the point of no return unless urgent action is taken.
"The opportunity offered by the Levelling Up Fund is potentially the perfect solution to this situation."