Federal Labor leader Bill Shorten has sought to appease the union movement by declaring he will personally intervene if the independent umpire cuts penalty rates on Sundays, but stopped short of promising to enshrine penalty rates in legislation.

More than a week ago Mr Shorten stated he would accept a drop on Sunday penalty rates if it was recommended by the Fair Work Commission.

The announcement angered unions and on Sunday they used the annual May Day Festival in Fremantle, WA, to send a message.

• Middle class set for tax cuts
• Government won’t comment on Manus
• PM’s big boost to cities plan

Secretary of the Shop, Distributive & Allied Employees’ Association Peter O’Keefe said it was concerning Federal Labor might so easily walk away from the issue.

Cafe workers want their Sunday rates. Photo: Getty

“[It is] an issue which is so fundamental to our members, and indeed members of many other unions whose penalty rates will be under attack in the months and the years to come,” he said.

Mr O’Keefe said it was Labor’s responsibility to support the union, and he had a clear message for Mr Shorten.

“You must leave no stone unturned, you must do everything you possibly can to protect penalty rates,” he said.

“If penalty rates are reduced you’ve got to do everything you can to have them returned back to where we say they belong.”

Mr Shorten attempted to appease the unions, and said he would fight any decision to cut penalties by writing to the Fair Work Commission — on Prime Ministerial letterhead — to seek a review.

“If Labor wins the election on July 2, I will intervene in the penalty rates case on behalf of the Commonwealth of Australia, to look after people who work unsociable hours, who deliver the services that we need and require,” he said.

“Labor is a defender of our penalty rates system, full stop.”

Unions demand penalty rates ‘lock, stock and barrel protected’

But his pledge fell short of union demands, who want penalty rates enshrined in legislation.

President of the Australian Council of Trade Unions (ACTU) Ged Kearney said penalty rates would be a defining issue in the upcoming election.

“Really we want to see them absolutely lock, stock and barrel protected,” she said.

WA Labor leader Mark McGowan was at the rally but appeared unaware that Federal Labor had softened its position.

“If you support an independent body to examine these issues you’ve got to accept that they will make rulings on these things,” Mr McGowan said.

“Bill has said that and I support what Bill has said.”

The Fair Work Commission has allocated more time for its hearings.

– ABC