A Liberal senator is calling on the government to have the 'courage' to take a plan for one weekend penalty rate for hospitality and retail workers to the next election.

Zed Seselja has broken ranks to back the recommendation from the Productivity Commission, despite Employment Minister Michaelia Cash stressing the rates are up to the Fair Work Commission.

'I don't think we should always be spooked by the fact that we had a WorkChoices election in 2007,' Senator Seselja told ABC radio on Wednesday.

Assistant minister Scott Ryan acknowledged Senator Seselja was free to air his view on the issue.

But the assistant cabinet secretary told Sky News the government's policy was for penalty rates to remain the Fair Work Commission's job.

Labor's Ed Husic said the Coalition wants to talk about changes, but the minute more questions are asked backs away.

'Every time you go to talk about a big issue with this government, the policy conversation they have is with one hand over their mouth,' he told Sky News.

'This isn't political courage, this is political cowardice.'

Senator Seselja believes reducing the Sunday penalty rate in the hospitality and retail sector would create jobs for the unemployed and more hours for those who now don't work that day.

'If it goes towards making it more likely businesses who want to open on Sunday can open on Sunday ... then I think there's some significant benefit in that,' he said.

He acknowledged it does take 'courage' to put such plans to voters, but said the government had that quality.

'Obviously, that's a decision for others to take,' he said.

Senator Cash has agreed to host round-table discussions on the commission's 70 recommendations in the new year, with any workplace relations changes to be taken to the next election for a mandate.

She insists she's not backing away from a fight.

AAP