Harriet Harman will today mark out the family as a key battleground in both the forthcoming Labour deputy leadership and the next general election.
The constitutional affairs minister will say that although Labour's victory in 1997 represented a "watershed", with the introduction of the minimum wage and more time off for parents among others, family policy is still the "poor relation".
Ms Harman - who polls suggest is leading the race for John Prescott's job - will also attack the Conservatives' new emphasis on family-friendly policies, saying they show "no readiness to go beyond warm words".
Tory leader David Cameron put the family at the heart of his speech to the party conference this autumn, and has promised tax changes for families including transferable tax allowances for parents and even mooted cutting tax on childcare.
But Ms Harman will warn: "For the Tories, talking about families is a way to show the Tories have changed and so win support.
"For us, it's not about getting votes off families but delivering for them, with the recognition that the family is key to our aim to tackle disadvantage and ensure equality in a strong economy and a fair society.
"The Tories will stop at warm words and will go no further. We have not shrunk from public investment and legislation and we must go further."
The constitutional affairs minister will acknowledge the difficulties of interfering in the family - last week, a report into the proposed new children's database said although it was aimed at protecting children, it was undermining the authority of the family.
A number of campaigners also warned that the government's efforts to tackle anti-social behaviour through parenting classes must not make parents "feel like a failure".
Ms Harman will say: "Family policy, is incredibly difficult territory. Any time government broaches the subject, parents feel judged.
"So, for example, when we press for more childcare for children of working mothers, mothers who are at home with their children feel criticised and mothers who are working feel they are being pressed to work even more.
"And when we argue for more rights for part-time workers, mothers working full-time feel blamed. So we need to be careful and we need to listen."
However, she will insist that these concerns must not prevent the government taking action on tackling low pay, the gender pay gap, flexible working and ensuring affordable childcare was available - all things that were crucial to health, strong families.
She will urge business leaders to "reflect on the sheer misery and anguish of hard-working parents bringing up children on a low income before they decry as unnecessary, proposals for greater legal rights".
Ms Harman will say: "Politicians in the 19th century did not simply exhort mill owners to limit children's working hours, to treat their infectious diseases and to teach child employees to read and write. They legislated and so should we."