CUPERTINO (CBS SF) – The long saga to redevelop the Vallco shopping mall in Cupertino could face another delay, as opponents of the project claimed they have enough signatures to place a referendum on the ballot.

The group Better Cupertino announced Tuesday that they have submitted 4,300 signatures to officials for review.

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The referendum challenges a decision made by the Cupertino City Council last month to approve a mixed-use project with nearly 3,000 housing units, along with offices and retail on the site.

Sitting mostly empty for the past several years, the fate of the mall has been subject to years of intense debate in the community, which included ballot measures in 2016. Last month’s decision by the council was preceded by 14 hours of meetings, stretching over two days.

Despite the referendum, Sand Hill Property Company said it still has the option to redevelop the site under SB 35, a controversial new state law that limits challenges by cities to affordable housing projects. The SB 35 plan, which also includes retail and offices, would include 2,400 housing units, half of them being affordable.

“This latest obstruction, and the 2-year delay it causes, gives the Community Plan no chance to catch up to the already approved and under-way Vallco Town Center project. We consider ourselves patient people, but our patience has finally run out,” Reed Moulds of Sand Hill said in a statement.

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Sand Hill said it would continue demolishing of the old mall, which began earlier this month.

Opponents have raised numerous objections to both plans, from potential traffic impacts, to overcrowded schools.

Project opponents also dispute that the project is covered by SB 35. Suspended Cupertino city attorney Randolph Hom filed an administrative claim against the city, saying he was retaliated against after claiming the project was illegal for several reasons, including inconsistency with the city’s general plan.

According to Better Cupertino’s website, the group said it would prefer retail on the Vallco site, no offices and fewer than 400 housing units, which it claims conforms with the general plan.

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About 2,900 signatures would need to be certified for the referendum to qualify for an upcoming ballot, likely in 2020.