The newly elected secretary of the Australian Council of Trade Unions, Sally McManus, says the Australian tradition of a "fair go" is under attack.
In an address to the National Press Club in Canberra, Ms McManus has called for raising the country's minimum wage by $45 a week.
"Our minimum wage once led the world. Now, it does not. It has been slipping rapidly down the rankings, and it's barely moved, in real terms, while bills have soared."
The Fair Work Commission reviews the minimum wage every year.
The ACTU always makes a submission, but the suggested $45 hike is one of its most ambitious to date.
Last year, the ACTU called for a smaller rise of $30 per week, and the commission only granted $15.
But opposition leader Bill Shorten has confirmed Labor will join the unions in pushing for a raise.
Shorten:"Today, Labor is making a submission calling for a fair and responsible increase to the minimum wage. Can the Prime Minister advise whether the Government has made a submission calling for a fair and responsible increase to the minimum wage? And by the way, Prime Minister, do you even know what the minimum wage is?"
Speaker: "Prime Minister has the call."
Turnbull: "Mr Speaker, it's $672.70 a week, as the Honourable Member would be well aware."
The Government has not yet revealed its own submission to Fair Work.
But one crossbench senator, David Leyonhjelm, says he disagrees with a $45 raise.
He argues Labor and the unions' pursuit of higher wages makes it harder for unemployed people to find work.
"The people who don't have a job deserve more concern than the people who do have a job. Now, going for that kind of wage rise in the absence of productivity to justify it - and that's a major condition - is job-killing. If employers are obliged to pay an extra $45 a week, they will employ fewer people, because they'll have less money to pay wages."
The country's largest business group is raising the same concerns.
The Australian Chamber of Commerce and Industry is calling for much less - a rise of just $8 a week.
Chief executive James Pearson says any rise must be small.
"The minimum wage is an entry-level wage, and, if it's too high, then small business simply won't be able to afford to offer jobs to those people who need them."
The Australian Retailers Association is also recommending a rise of $8 a week.
That translates to a 1.2 per cent increase in the minimum wage, below the current rate of inflation.
That means it would be a reduction in wages relative to the cost of living.
The Fair Work Commission is expected to make its decision in May, with wage changes coming into effect in June.
