Labour Party leader David Shearer has signalled his party might make some concessions to get support from the National-led Government for its paid parental leave policy.
A member's bill from Labour MP Sue Moroney proposes to increase paid parental leave from 14 weeks to 26 weeks by 2014.
Mr Shearer says the policy could be phased in over a longer time to help ease the cost to the Government.
He has written to Acting Prime Minister Bill English asking him to take part in the debate.
But Mr English says he is not planning to take up Mr Shearer's offer and is still warning he will use the Government's financial veto to block the bill.
He says the Government has already committed significant extra money to helping families, including increasing working for families tax credits and spending more on early childhood education.