Schools should take children from the age of two or three to improve the chances of poor youngsters, the chair of Ofsted has suggested.
Many young children from disadvantaged backgrounds have had a "dire" start to their education, and are around a year and a half behind their richer classmates at the age of five, according to Baroness Sally Morgan.
Exposure to poor parenting, diet and housing means that often they are not ready to start formal schooling, she said.
At an event in central London organised by the ARK schools academy chain, Baroness Morgan called for a "big brave move" in early years education, with more nurseries attached to schools and a particular focus on the poorest children.
Increasing numbers of schools are becoming "all-through" - taking pupils from ages five to 18 and this should be extended to at least age three to 18, she argued.
A report published by Ofsted in the summer revealed that poor five-year-olds are 19 months behind their more affluent peers.
"W hat a dire start to their educational life," Baroness Morgan said.
"Those children had low level social skills especially reading and communication. They're not ready to learn at school. Weak parenting, low educational attainment of parents, poor diet, poor housing and so on. The gap between affluent and disadvantaged is greatest in that group."
No-one has yet got a grip on this problem, she said.
"I think there needs to be a big brave move on the under-fives agenda to target funding heavily on the children who will benefit most and increasingly I think to look to strong providers to go further down the system. We've increasingly got five to 18 schools, why not three?"
Speaking after the event, Baroness Morgan said that it was an "obsession" of hers that support is not getting to the poorest children early enough.
Getting them into pre-school early on means that are much more likely to start formal school at age five ready to learn, she said.
" At the moment a lot of children from really disadvantaged backgrounds aren't ready to learn and the school almost has to provide nurturing before it can start to educate.
"I said three to 18, it could be two to 18 as far as I'm concerned."
She added: "Whereas all governments in a sense have really focused on the needs of disadvantaged schoolchildren, I don't think any government has sufficiently focused on the needs of disadvantaged under-fives. I think that's cross-party."
Getting children into school ready to learn would have a "transformative" effect, Baroness Morgan said.
She added that it was her personal view that the pupil premium - which is money targeted at the poorest schoolchildren - should be extended to disadvantaged under-fives.
All schools capable of having a nursery should do so, and for the poorest children the focus should be on ensure there are good nursery places for them.
Baroness Morgan's comments come on the day that Ofsted's new tougher inspection system for nurseries and pre-schools comes into force.
Under the shake-up only a rating of "good" or "outstanding" will be considered acceptable, and those that fail to meet these standards will be at risk of closure if they do not rapidly improve.
The move is likely to affect thousands of nurseries and pre-schools currently caring for young children in England.