Free childcare is being extended to another 260,000 toddlers from low income families under new Government plans.
Deputy Prime Minister Nick Clegg said the extension of the scheme for two-year-old children would cover the 40% of families "most feeling the squeeze".
The Liberal Democrat leader said his party wanted to widen the free support to all two-year-olds but acknowledged there were "limited resources".
Households in England that qualify for free school meals are already eligible for 15 hours a week of free childcare.
As part of a £760m package, the policy is being extended to families on working tax credits who earn less than £16,190 per year.
The announcement came as a new survey revealed more than 70% of non-working mothers stay at home because childcare costs would leave them worse off.
The Asda Mumdex poll, which questions 5,500 mothers, also found new mothers were most worried about money (54%) even before their own health (30%).
Almost three in five (57%) said they wanted schools to find a way of caring for children until their parents finished work.
Mr Clegg said: "All the evidence shows that if you take two children - two five-year-olds hanging up their coats next to each other on the first day of school - the poorer child will already be behind their better off classmate before a single lesson has been taught.
"Without this help, children suffer and the whole class suffers as teachers have to focus more of their efforts on children who are frustrated and left behind through no fault of their own.
"I believe that every British family, whatever its structure, background and circumstances should be able to get on in life."
Mr Clegg said that adopted children, those in care and youngsters with a disability or special educational needs will also benefit from the changes which are to be brought in next September.
Critics however are concerned that the budget will not rise to match the doubling of numbers benefiting from the scheme.
The Government will spend £534m on the scheme this year which will rise to £760m in 2014.
The Pre-school Learning Alliance warned the Government plans would fail if they were not properly funded.
Chief executive Neil Leitch said: "This is a tremendous initiative that will help to support young children who statistically run the risk of being marginalised throughout their entire life."
But he added: "Our fear is that should this well-intentioned initiative be grossly under-funded, the Deputy Prime Minister will not achieve the brighter start in life for these children that he wants."
Anand Shukla, chief executive of the Family and Childcare Trust, voiced fears that nursery closures could impede the delivery of free childcare.
"We are concerned that loss of nursery provision in children's centres is impacting on local authorities' ability to find sufficient places for the offer," he said.
New research by the Family and Childcare Trust, to be published later this month, indicates that a minimum of 108 nurseries across England have closed or were never commissioned as they were supposed to be, he added.
Shadow education secretary Stephen Twigg claimed the Government was failing to deliver the extra nursery places needed for the measures it had already announced.
"Whilst parents are feeling the squeeze of childcare, the Prime Minister has presided over reduced support, rising costs and fewer places," he said.
More From Sky News