Large retailers that kept their doors open but claimed business rates have been urged to put cash towards helping people shut out of financial support schemes.
Greater Manchester Mayor Andy Burnham suggested other big firms follow Tesco's example, which said on Wednesday that it would repay £585million it had received in tax relief during the pandemic.
The supermarket giant said the financial support had been a "game changer" but it had weathered the worst of the crisis and intended to return the cash.
Mr Burnham said the move by Tesco could “offer the glimmer of a solution” to helping millions of people excluded from Rishi Sunak ’s financial support schemes.
Campaign group Excluded UK estimates around 3 million taxpayers, including 1.6 million self employed people, are not eligible for Covid support measures.
Mr Burnham made the call at a virtual event with campaigners and other Metro Mayors, including London’s Sadiq Khan and Liverpool City Region’s Steve Rotheram.
“They are not the only big retailer who stayed open and made a lot of money this year through their sales but also benefited from business rates,” he said.
“One idea is whether we ask others. We don’t blame them for taking it because it was always going to be a very unpredictable year.
“But now they are at the end of that year, maybe we could ask people who don’t need that money or don’t need the furlough money they had to pay it back, and that fund becomes the fund for our excluded and the people who have been forgotten.”
Tory West Midlands Mayor Andy Street said he was baffled by why the Treasury was refusing to change course.
Gaps in support at the start of the pandemic were "understandable" but should have been fixed, he said.
The mayors heard heartbreaking stories from people struggling to survive without access to financial support.
Chloe Savage, a professional embroiderer, said her teenage daughter had started self harming due to the stress and starving herself because she wanted to cut the family’s food budget.
Amanda Richardson, who supplies animals for children’s parties, broke down in tears as she said her animals were facing “a death sentence”.
Sonali Joshi, founder of Excluded UK, said gaping holes were obvious in the furlough scheme and the self employed income support scheme back in March - and welfare had not provided an adequate safety net.
She said: "The end result has been poorly targeted schemes, creating huge disparities.
"With the schemes now extended until March, without the help so urgently needed for those who have been excluded, this will represent a whole year for so many, on little to no income."
People from all walks have life have been affected, she said, ranging from freelancers to the self-employed.