Labor leader Bill Shorten has responded to Malcolm Turnbull's vow to fight an election on trade union reform, taking to Twitter to declare: "Bring it on".
After the release of the trade union royal commission's final report on Wednesday, Mr Turnbull flagged major reforms to union governance and vowed to make it an election issue if the Senate blocked new laws.
On Thursday Mr Shorten, who is on leave and did not front the media on Wednesday, tweeted: "If Mr Turnbull and his Liberals want to fight an election on industrial relations, bring it on. We won on WorkChoices & we'll win again."
In a separate statement sent to Fairfax Media, Mr Shorten said he would "welcome any day of the week" Australian voters stacking up his record against Mr Turnbull's on workplace relations.
Mr Shorten said the government was using the commission's report as "a smokescreen for its full-scale attack on penalty rates".
He was referring to a Productivity Commission paper released before Christmas that found penalty rates for Sunday work should be dropped to the same rate as Saturday penalties.
Meantime, the construction union claims former workplace relations minister Eric Abetz was lying when he said the royal commission would shine a light on both unions and private companies.
The labour movement was excoriated by the commission on Wednesday: its final report found it was beset by "deep-seated" misconduct.
The report also referred a number of companies to police and prosecutors. They included engineering firm John Hollandand food grower Chiquita Mushrooms, which it found may have engaged in corrupt conduct, and Winslow Constructors in relation to possible false accounting.
Senator Abetz had previously said the commission was "a sword that will cut both ways". However Dave Noonan, national secretary of the CFMEU's construction division, said examples of companies that "behaved appallingly" were raised with the commission but ignored.
"When Senator Abetz said the sword would cut both ways, he was lying. He knew the terms of reference were narrow and designed only to scrutinise unions," Mr Noonan said.
"In every case where there was employer misconduct, the royal commission did their best to sweep that under the carpet and focus on the real or imagined shortcomings and misdeeds of unions and their officials."
He said allegations relating to worker deaths, problems with the payment of superannuation and immigration fraud were ruled outside the inquiry's terms of reference.
Senator Abetz said issues such as workplace safety were legitimate, but an inquiry into trade union governance was not the place to examine them. He described Mr Noonan's comments as "ludicrous" and said the commission drew attention to numerous instances of wrongdoing by companies and their managers.
"David Noonan can't overcome the devastating findings of the royal commission by trying to set up straw men to attack me and divert attention," he said.
"The simple fact is he's presiding over a corrupt union. Most people are of the view that he must know what is going on within his union and all he has done is basically run defence for them rather than being at the vanguard of stripping out the corruption."
In a statement, the Australian Council of Trade Unions said companies that break the law "should adhere to the same consequences as everyone else".
John Holland Pty Ltd declined to comment. Chiquita Mushrooms and Winslow Constructors could not be contacted.