He reiterated that, if they were cut, minimum penalty rates should be included in National Employment Standards. The NES are 10 minimum employment entitlements that have to be provided to all employees and include maximum weekly hours, annual leave, and public holidays.

With the exception of the Electrical Trades Union, union leaders had previously swung behind Mr Shorten this week, warning the Greens' proposal would allow the Coalition to cut the minimum wage and other employee entitlements.

While ACTU president Ged Kearney had on Sunday called on Labor to take more action to protect the take-home pay of employees, Mr Oliver said backing the Greens' proposal would open the way for the Liberals to cut conditions with the "stroke of a pen".

But Mr Hilakari said he did not believe a future Coalition government would get such proposals through the Parliament because it would prompt a major backlash from voters. "Good luck trying to do that," he said.

Employment Minister Michaelia Cash said on Thursday the Coalition did not support legislating penalty rates.

"The government maintains that the setting of penalty rates is a matter for the independent Fair Work Commission," she said.

She sought to revive evidence to the Heydon trade union royal commission about enterprise agreements struck by the Australian Workers Union when Mr Shorten was its Victorian and national secretary.

"While Bill Shorten talks tough when it comes to penalty rates, his actions speak louder than words," she said.

"It must never be forgotten that he is the only member of parliament who had the ability to directly influence penalty rates for some of Australia's lowest paid workers, and when given the opportunity, he stripped them away."





