A poll of 1,800 parents, conducted by Computershare Voucher Services, found that 57% would not be able to continue with their existing childcare arrangements without the vouchers.
A huge majority of the parents surveyed (98%) disagreed with the proposal, announced by Gordon Brown in October, to phase out tax relief on the vouchers. After April 2011, there will be no tax breaks on new childcare voucher schemes that are set up, so they will once again become a cost to employers.
Simon Moore, managing director of Computershare Voucher Services, said: "Parents believe that having this benefit removed could prevent them from being able to work. Tens of thousands of people across the country have now called on the prime minister to rethink his decision. Vouchers are a valued and a successful initiative that help parents, particularly mothers, to get back to work."
The number of people that have signed a Downing Street petition calling on Brown to rethink his proposal has reached 75,000 - making it the most popular e-petition on the number10.gov.uk website
Earlier this week it was revealed that nine ex-ministers had written to the prime minister urging him to rethink his controversial plans to scrap tax-exemptions for childcare vouchers. The letter came from the Progress think-tank and its signatories include former Cabinet members - among them Patricia Hewitt, Estelle Morris, Hilary Armstrong, Beverley Hughes and Caroline Flint.
The Federation of Small Businesses and The Daycare Trust have also already expressed opposition to the plans.
The vouchers currently enable working parents to make significant savings on the cost of their childcare, as they can opt to receive £243 of their pay each month in vouchers before income tax and National Insurance is deducted.
