The Coalition's paid parental leave (PPL) scheme continues to come under fire, with the major parties rowing over the fairness of the plan, which Tony Abbott has described as his "signature policy".

Labor is continuing to focus its election attack on the scheme, with Prime Minister Kevin Rudd describing it as "unfair" and Finance Minister Penny Wong saying the policy is "in tatters" amid questions over how it will be funded.

Opposition Leader Tony Abbott has rejected the criticism, saying the Coalition is "at the forefront of embracing an important social reform".

The Coalition wants to introduce a 26-week replacement wage scheme where women earning up to $150,000 a year would be paid their full salary for the period of leave, including superannuation.

For a woman earning $150,000 per annum or more, the leave would be capped at $75,000.

Part of the scheme would be funded by a new levy on big business, but the Coalition also expects the states and territories to contribute the money they already spend on parental leave.

At $5.5 billion a year from mid-2015, the policy costs three times the current scheme, and economists and big business have voiced their concerns over the generous proposal.

Speaking in Brisbane this morning, Mr Rudd said the Opposition Leader must tell voters how he intends to fully fund the policy.

"We believe in reasonable and affordable paid parental leave, we do not believe in one which is unaffordable, unfair, uncosted and frankly, one which is going to be offered at the expense of basic services for all Australian families," he said.

"The priorities which Mr Abbott is now talking about have to do with his version of paid parental leave.

"I don't know if you've studied the detail of this but Mr Abbott, his belief in a fair go is that a certain select group of families... should be given $75,000 worth of paid parental leave... while ripping $15,000 out of the pocket of 1.3 million families with the school kids bonus."

But Mr Abbott contends the Prime Minister "just doesn't get it".

"This isn't a question of being generous, this is a question of being fair," he said while campaigning in Geelong.

"Why should the people in Kevin Rudd's office go on paid parental leave at their wage and people working as shop assistants and factory workers and charity workers not get paid parental leave at their wage too?

"I think a lot of Labor Party people are embarrassed that on this particular issue it is the Coalition which is at the forefront of embracing an important social reform based on the best values of the Australian people."

Abbott moves to allay state concerns over PPL

Labor's renewed criticism of the policy comes after Western Australia's Liberal Premier described the PPL scheme as "too generous".

Colin Barnett said yesterday while he supports paid parental leave, WA would not be contributing any extra money to the Coalition's scheme.

"I think in many respects it probably is too generous but we'll see what comes at the end of the day," he said.

"If Tony Abbott becomes prime minister and that scheme is introduced we will cooperate in terms of the administration, but we will not be contributing money to the scheme."

The Coalition says, if elected, it would bridge the gap between the cost of state parental leave schemes and the national one.

Where do the parties stand on paid parental leave? Not sure about the state of play? Inform your vote using our policy page.

Mr Abbott said today he would not be asking the states for any more money.

"If we really want the women of Australia to be first-class citizens and first-class contributors to our economy, as well as to our society, they need to have a proper choice to combine families with careers. It is very important," he said.

"As for the premiers, we will sit down with them and we will have an adult discussion about this.

"I am very confident when they understand that there will be no cost to the states, what there will be in fact is an improvement to their existing schemes, as well as an improvement to the situation of every woman in the workforce, they will come with us."

Despite Mr Abbott's reassurance, Senator Wong says divisions remain within the Coalition in relation to the plan.

"We've seen National Party MPs who say they don't support the scheme but they will keep quiet in exchange for Liberal Party pork-barrelling in their region," she said.

"In Victoria, one of the role models of Tony Abbott, Jeff Kennett, has called this plan an extraordinary extravagance.

"So this is a plan that is in tatters. They can't deliver it. They're divided on it but, most importantly, most importantly for Australians is this - they can only fund it by engaging in massive cuts."

Speaking to Fairfax radio late yesterday, the Opposition's treasury spokesman Joe Hockey tripped over the PPL figures.

At first he said "100 per cent" of the scheme's cost would be funded by the levy on big business.

He quickly corrected himself, but could not give an exact answer.

"Well it has to be at least 50 or 60 per cent, 60 or 70 per cent. But I'm not going to speculate because it is - I haven't got the numbers in front of me, in a car," he said.