Malcolm Turnbull has accused Bill Shorten of lying in a new robo-call blaming the Prime Minister for a decision to cut Sunday penalty rates. Picture: Sam Rosewarne

Party faithful are being asked to chip in $5 to help print thousands of bumper stickers to “stick it to Malcolm”.

The design reads: “Malcolm Turnbull, Hands Off Our Penalty Rates”.

Labor National Secretary Noah Carroll has called on supporters to help keep the issue on the agenda.

“Malcolm Turnbull wants the issue of penalty rate cuts to just go away,” he said in an email today.

“When the stakes are a sudden pay cut to 700,000 of Australia’s lowest-paid workers, we can’t let that happen.”

Anyone who donates will have stickers sent to them.

Labor Party bumper sticker over penalty rates.Source:Supplied

“If thousands and thousands of us plaster them across the country, it will help ensure that every day until the next election, Australians are reminded that this Government supported a pay cut for workers, while giving a tax cut to big business,” Mr Carroll says.

It comes after the Prime Minister this morning slammed a new robo-call by leader Bill Shorten on penalty rates as a lie.

The call begins: “Malcolm Turnbull’s cuts to penalty rates will mean 700,000 workers will lose up to $77 per week.”

Speaking to 3AW radio station this morning, Mr Turnbull said: “He’s lying, just like he lied to you.”

“He was here in April last year and said he would support the decision of the Fair Work Commission on penalty rates even if they resulted in a reduction in Sunday penalty rates to bring them closer to Saturday penalty rates,” Mr Turnbull said.

The Opposition leader later defended the call.

Mr Shorten was questioned by reporters in Canberra on whether the line was a lie as the decision was in fact made by the Fair Work Commission.

“What is the point of being Prime Minister if you are never going to stand up for workers,” Mr Shorten responded.

The Labor leader said Mr Turnbull had previously intervened in the decisions of independent umpires on the pay rates of truck drivers and Victorian firefighters.

“He has the power to stop this mistaken decision; he chooses not to,” Mr Shorten said.

Earlier, Mr Turnbull told radio station 3AW he supported the independent umpire’s call to reduce penaly rates but it was not the government’s decision.

“Shorten has no regard for the truth, any more than Sally McManus has for the rule of law,” he said.

Prime Minister Malcolm Turnbull has not ruled out changes to superannuation rules in the May budget. Picture: AAPSource:AAP

In the wideranging interview Mr Turnbull would not be drawn on reports the Government will look at changing superannuation rules in its May budget to allow first home buyers to dip into their retirement savings for a house deposit.

He was also asked whether he was critical of the National Australia Bank’s decision to increase interest rates for new and existing investor home loan.

“It’s up to the banks to justify it Neil, that is their responsibility,” Mr Turnbull told host Neil Mitchell.

“They’ve got to come forward and explain it and they’ve got the opportunity to do so, and indeed the obligation to do so regularly, before the Parliament.

“They’ve got to recognise that increasing interest rates puts pressure on households, on families, on businesses.

“They’ve got to prove that they’re not just simply trying to up their profits at the expense of their customers.”

When quizzed further, Mr Turnbull said he believed the bank would justify the move by referencing the increase in their cost of funds and the increase in rates in the US.

But he said if the banks did not justify the move, customers would look elsewhere.