Those branches represent, in total, just over 100,000 union members, the analysis of membership disclosures to the Registered Organisations Commission shows. 

Mr Setka’s key backer has been the Electrical Trades Union’s Troy Gray who has offered vigorous public support and saying he has been victim of a "political stitch up". Mr Gray was behind calls on Wednesday that Labor politicians be audited for any history of domestic violence allegations.

Mr Setka has also received public support from Luba Grigorovitch, Victorian secretary of the 7500-member Rail, Tram & Bus Union.

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He has won public support from the branches of the union's construction division in NSW and Western Australia but not Queensland. National construction union leaders have been meeting on Wednesday.

Mr Setka has been suspended from the Labor Party and leader Anthony Albanese wants him removed from the party, and he has been under intense pressure to resign from his union role since last Thursday, when Ms McManus made a strong statement calling on him to go.

"I told him it is in the best interests of the union movement that he resigns," Ms McManus said. "There is no place for perpetrators of ... violence in leadership positions in our movement.

The resignation call has been reported as splitting the union movement, but in reality, the vast bulk of unions support Ms McManus.

Last month, Mr Setka's lawyer indicated to a Victorian court that the construction union leader would plead guilty to using a carriage service to harass a woman.

He would also plead guilty to a count of persistently breaching a court order. Mr Setka will return to court next Wednesday for a plea hearing. The woman cannot be named for legal reasons.

But the issue only escalated after The Age revealed on June 8 leaked graphic details of his alleged harassment of a woman as well as his leaked comments about Rosie Batty.

Police analysis of Mr Setka's phone activity reveals on a single evening last October, he called the woman 25 times and sent her 45 text messages. In the messages he called her a "weak f---en piece of shit" and a "treacherous Aussie f---en c---" and a "f---en dog".

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A witness, a former judicial figure, described how Mr Setka had allegedly repeatedly intimidated and terrified the woman over several months.

The Age also reported leaked comments from Mr Setka at the national executive of the CFMMEU, where he linked Ms Batty's advocacy with men having fewer rights.

That created a political and media storm and led to the push for his expulsion from Labor.

Mr Setka has said his comments about Ms Batty were taken out of context but in an interview with online publication The New Daily he confirmed the key details of what had been originally reported.

On Monday, the National Tertiary Education Union said the public focus on Mr Setka was causing damage to the union movement as it called for him to resign.

"(It) impacts on the work all unions do towards ending domestic violence, ensuring safety at work, and improving the lives of workers," the statement of national NTEU officers said.

"It also provides ammunition to those seeking to further limit and constrain unions from properly representing workers."

The Transport Workers Union said unions were "among the most democratically run organisations in our community and members views should be respected".

"However as one of the true scourges on our community, issues regarding domestic and gendered violence are of the utmost importance to our society as a whole.’’