Labor remains concerned stripping new mums from the modest federal paid parental leave scheme should their employer provide its own scheme will hurt low and middle income earners.
The Turnbull government is pursuing an end to what former Liberal treasurer Joe Hockey labelled "double dipping" - a term present ministers like Social Services Minister Christian Porter are now keen to avoid - which would save $1.2 billion over the next four years.
Labor frontbencher Brendan O'Connor mocked the coalition government as one of extremes on paid parent leave.
Under Tony Abbott it wanted a "Roll Royce" paid parental leave scheme and now under Prime Minister Malcolm Turnbull it wants to hit low-income new mothers, he said.
"We are worried most of all about predominantly those women on low and middle incomes who will actually be affected by this," Mr O'Connor told Sky News on Sunday.
The federal PPL provides the minimum wage for 18 weeks.
Mr O'Connor said a retail worker for example would lose $5300 while on maternity leave.
The opposition workplace spokesman said Senate powerbroker Nick Xenophon made a commitment not to change the paid parental leave arrangements before the election and will want to be perceived as an "honest politician".
Senator Xenophon and his team command three crucial seats in the upper house.
Mr Turnbull wouldn't give a direct answer when asked if Senator Xenophon doesn't support the PPL changes how he will get the bill through and fill a $1 billion hole in the budget.
"All of these matters are being negotiated with the Senate as you know," the prime minister told reporters in Sydney.
"We don't have a majority in the Senate, so the passage of legislation has to be negotiated."
