Business groups are demanding the City Council block a controversial labor bill backed by Mayor Zohran Mamdani and his progressive comrades — arguing it will slap crippling mandates on crucial job providers.

The coalition, including the Taxpayers Protection Alliance and the American Consumer Institute, fired off a letter to the Democratic-led council and Speaker Julie Menin on Tuesday warning that the proposed Delivery Protection Act would come at “substantial cost’’ to companies such as Amazon and UPS — and thus consumers.

“These requirements would impose substantial costs on businesses while doing little to address the underlying safety concerns the legislation purports to solve,” the letter said.

The bill, sponsored by left-wing Council Member Tiffany Cabán and backed by Mamdani and other progressives, would streamline safety training and operations for delivery companies — while prohibiting them from using third-party contractors or gig workers to complete their fulfillment process.

Companies that don’t comply would have to pay a $500,000 financial penalty to the city Department of Consumer and Worker Protection per non-employee worker.

“By placing significant new obligations on facilities that use contracted workers and imposing a $500,000 bond for every non-employee delivery worker- the legislation creates a powerful incentive for businesses to abandon independent contracting altogether,” the opposition coalition wrote.

Amazon has already threatened to close more than a dozen warehouses and move thousands of workers out of New York City because of the bill.

The business groups opposing the potential legislation cited an op-ed penned in the Washington Examiner that said 38% of all workers in the US earn money from temporary work and claiming the sweeping proposed Big Apple policy could cost residents roughly $664 per year through passed-on costs. The coalition also warned that the proposed requirements could disproportionately affect small businesses because they are at a disadvantage when it comes to adjusting to large-scale administrative changes.

The suggested measures also would curb competition among large corporations and contractors if they can’t hack the measures, either, foes said.

“Ironically, legislation intended to hold large corporations accountable could therefore make the market more concentrated by pushing independent operators out of it,” they wrote.

But the popular bill already has 35 co-sponsors – giving it a veto-proof majority if it goes to a council vote – along with the backing of delivery-worker unions such as the International Brotherhood of Teamsters and the Workers Justice Project.

The bill is currently laid over in committee – where it is awaiting a vote before being considered by the entire 51-member council.

A committee vote has not yet been scheduled, according to the council’s website.