ACTU secretary Sally McManus will step up demands on Shorten on Wednesday by calling for a 6 per cent increase in the minimum wage this year and a 5.5 per cent increase next year.
The union demands are certain to be opposed by employers who argue that the minimum wage has increased ahead of inflation in recent years and that bigger boosts would make it harder to hire workers, keeping people out of jobs.
The bald fact is that Shorten cannot guarantee a specific wage increase unless he dictates terms to the independent umpire, an extraordinary intervention.
This is not the only issue where Shorten is raising expectations.
On climate change, for instance, he is yet to decide whether to use carry-over credits from the Kyoto agreement toward his goal of reducing emissions by 45 per cent by 2030 and meeting the global Paris agreement.
The argument about the carry-over credits has been running for weeks, with concerns from some Labor members who believe it would be wrong to use them, but Shorten and his shadow cabinet cannot say what they will do.
Shorten fended off questions from journalists about his policies on Tuesday.
“I know you guys want me to do the whole campaign launch today,” he said. Nobody expects that.
What voters should expect is greater detail before the rush of the election campaign. Wage rates and climate change are two of the biggest issues in federal politics. Shorten is making big promises on both. He needs more convincing answers on how he would deliver.