Flanked by his wife Margie at a childcare centre in western Sydney on Tuesday, Mr Abbott talked up his idea for a Productivity Commission inquiry into whether taxpayer-funded subsidies should be extended to nannies.
The federal government has dismissed the idea as welfare for the rich.
But one union leader has given it his backing, and the Greens are pushing for more flexible childcare options.
Mr Abbott is pursuing his idea, arguing it is an important issue for many Australian families.
"It has an enormous impact on the productivity of the mothers of Australia," he told reporters.
"The mothers of Australia should be economic assets as well as social assets."
If mothers wanted to be bigger economic contributors they should have the opportunity to do so, Mr Abbott said.
Joe de Bruyn, head of the powerful Shop Distributive and Allied Employees Association and a member of Labor's national executive, says the current system discriminates against families who wish to have their children cared for at home.
"People who make their own arrangements through families, friends, neighbours do not get any benefit whatsoever," he said.
The Australian Greens say taxpayer-subsidised nannies are not a "silver bullet" for childcare issues.
But Greens senator Sarah Hanson-Young backs a Productivity Commission inquiry into the state of child care and early education services.
"We know that long-day care doesn't suit a lot of families," she told reporters in Adelaide.
"We know that a lot of families are doing a lot of combination care."
Senator Hanson-Young said there was a case for flexible options.
Pretending there is no need, as the Labor government has done, is "just bollocks", she said.