David Cameron has pledged to more than double the number of health visitors as part of a drive to push family-friendly policies.
The Tory leader told his party's spring forum in Gateshead he wants a "universal health visiting service".
The cash will come from scrapping plans for more outreach workers for SureStart family centres, he said.
Minister for Children Beverley Hughes said SureStart was a "vital frontline service" that deserves Tory support.
Health visitors have gone down since 2004 but Labour says there are more community matrons and school nurses.
The government has also pledged to ensure SureStart family centres in deprived areas are given two outreach workers, to encourage families to use their services.
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It's been shown that a lot of money spent on SureStart schemes has been wasted
L. Richardson, Hadleigh
Mr Cameron said: "I don't have a problem with that, but money is tight and we have to make choices.
"Instead of more untrained outreach workers, we need more trained professionals who really know what they're doing," he told Tory activists.
"They're called health visitors. Highly-trained NHS professionals who come to your home and build up a trusting, personal relationship with the family."
Private poll claim
He added: "We're going to increase the number of health visitors by 4,200 - that's a more than 50% increase. And we're going to boost support for those who live in the most deprived areas.
"This would make it possible for every mother to get two home visits before the birth of their child, six hours home support in the first two weeks, a visit every two weeks in the first six months, monthly visits in the next six months, and two visits a year between the ages of one and five."
However, the children's minister said SureStart is already making a "real difference".
"Outreach workers ensure that the most disadvantaged families access the wide range of services SureStart offers including health services, childcare and employment advice.
"David Cameron should support SureStart, not constantly try to undermine it. Scrapping this vital front line service will hit the poorest most."
Labour claims Mr Cameron has decided to push family policies after private polling warned that people move away from supporting the Tories when they have children - something denied by the Conservatives.
Mr Cameron has also faced criticism for allowing TV cameras into his home to film him with his own children.
Mr Cameron risked controversy yesterday by allowing ITV News to film him sharing breakfast with wife Samantha and their children Ivan, Nancy and Arthur, to help promote new family-friendly proposals on parental leave.
Prime Minister Gordon Brown made clear that he would not give similar media access to his young sons John and Fraser.
But Mr Cameron insisted that it was "a perfectly natural thing to do".
"I am asking people a really big thing, which is to make me their prime minister, and I think if you do that, people have a right to know a bit about you and your life and your family and what makes you tick and informs your thinking," he told BBC News.
"Nothing informs my thinking more than my family. It's the most important thing in my life, so I think it's a perfectly natural thing to do."
David Cameron said money for health visitors will be found
On Friday, the Conservatives announced plans to let new mothers and fathers share their 52 weeks' leave after the birth of a baby.
Mothers would be able to go back to work at any point after the first 14 weeks and leave fathers looking after the child, or both could take six months off together, under the Tory plans.
Shadow chancellor George Osborne, in his keynote conference speech, said Wednesday's Budget would make life harder for families feeling the squeeze from higher food bills, rising petrol prices and increased mortgage repayments.
"Government should be there to help people when times are tough and family budgets are tight," said Mr Osborne.
"But this government has taken the cost of living and added to it."
He criticised the government's decision to blame Britain's tough economic climate on problems in the US housing market, saying it was "not the sub-prime estate agent in Mississippi who's forcing us to borrow £140 billion - it's Gordon Brown."