Labor scrambles on penalty rates

The Greens are pushing ahead with their plan to legislate weekend penalty rates despite a Labor charge it could open the door to a conservative government doing away with them.

The minor party has Labor scrambling for a consistent position on a Fair Work Commission ruling on Sunday penalty rates for hospitality and retail workers.

A decision to reduce the Sunday rate to Saturday levels could be made before voters go to the polls on July 2.

Labor was tying itself in knots on Monday as leader Bill Shorten and workplace relations spokesman Brendan O'Connor tried to walk a fine line on the issue.

On the one hand, Mr Shorten is on the record saying he will respect the commission's decision.

On the other, Labor wants to promote itself as the protector of "our penalty rates system" to use the Labor leader's words.

But it won't follow the Greens by enshrining weekend penalty rates into law.

Doing so was dangerous, Mr Shorten said - warning it "loaded the gun" for a conservative government to "pull the trigger" and abolish penalty rates.

"What the government has the power to put in, a future government has the power to dismantle," the former Australian Workers Union national secretary said.

Instead if Labor wins power on July 2 and a commission decision is pending, it would lodge a government submission opposing any change.

Mr O'Connor had more difficulty explaining Labor's position when quizzed by Neil Mitchell on radio 3AW in Melbourne.

He declined to say "yes" when asked seven times whether he supported Mr Shorten's past statements on the issue, backing the independence of the umpire.

When asked if he could guarantee weekend penalty rates would not be cut under a Labor government, Mr O'Connor said: "The umpire makes these decisions."

Earlier, another Labor frontbencher Kim Carr appeared to favour legislation if the commission came down in favour of employers.

The Greens say it's not good enough for Labor to merely put a case to the commission.

"They talk tough on protecting weekend rates but will not do anything to protect weekend rates should they be cut," workplace relations spokesman Adam Bandt told AAP.

He also dismissed as an "absolutely ridiculous proposition" Labor warnings about setting a legislative precedent with its plan.

Rates and other employment conditions such as annual leave were legislated in existing awards, Mr Bandt said.

"The question is whether Labor has the guts to put that into legislation or whether Labor is going to wash their hands of it."

ACTU president Ged Kearney said unions wanted to see more protections for penalty rates, leaving the door open to supporting legislation.