Malcolm Turnbull insists his government is not "union busting" as it fast-tracked legislation cracking down on union corruption for the second time in 24 hours.
The prime minister on Wednesday argued the case for establishing a registered organisations commission, rejected three times by the Senate.
"We fought the election on these commitments to workplace reform and we won," he told MPs.
"This was never about union busting, it is about economy boosting."
The legislation passed parliament's lower house for a fourth time.
Mr Turnbull says the system was doing very little to deter union corruption and accused officials of treating small fines for misconduct like parking fines.
The government suspended usual process to bring on a truncated debate on its bill after using the same manoeuvre the day before to restore the building industry watchdog.
Mr Turnbull argued his government had a clear mandate and pointed to the trade union royal commission findings as evidence the case for change had been made.
"The time for action to stop these scandals, to end the rip-offs is long overdue," he said.
But opposition employment spokesman Brendan O'Connor accused the government of ideologically attacking unions.
"They see unions as an obstacle to their true mission - a low wage, easy to hire, easy to fire society," he told parliament.
"A race to the bottom on pay and conditions."
Mr O'Connor accused the prime minister of pulling the legislation out of the bottom draw because the government had nothing else to talk about.
Despite sending voters to a double-dissolution election, the bills were only mentioned by the prime minister a handful of times during the eight-week campaign.
Mr O'Connor labelled Mr Turnbull a "weak, pathetic sellout" who was boring his own backbench.
"They're stuck watching this bad tribute act, this cover band butchering the Abbott government classics," he said.
The bills were first introduced by former prime minister Tony Abbott.
Manager of opposition business Tony Burke complained new MPs had not had the opportunity to debate the bill.
Labor insists there is sufficient oversight of unions already.
Labor will attempt to amend the legislation so that it gives the Australian Securities and Investments Commission power to investigate breaches, rather than the proposed new commission.
It would also double maximum penalties for criminal charges and increase fines for misconduct from $10,800 to $216,000.
Labor also wants to reduce the political donation disclosure threshold from $13,000 to $1000 and prohibit anonymous donations above $50.
