Unions are on track to spend tens of millions of dollars as part of their bid to overhaul Australia’s workplace laws and turf out the Morrison government.

The ACTU spent $10.7 million in the 2017/18 financial year, political expenditure disclosures to the Australian Electoral Commission show.

The spending, including on its 'Change the Rules' campaign, dwarfs the outlay of big business lobby groups for the same period.

Tens of thousands of people march through the streets of Melbourne in support of the Change the Rules campaign in 2018. Victorian Premier Daniel Andrews led the march. Credit:Justin McManus

Much of the ACTU’s spending was on TV advertising, with $8.8 million spent on the "broadcast" of political issues.