Rogue construction union boss John Setka is already in fights with the Labor party and the ACTU leadership. Now he faces a battle with parliament.

Centre Alliance senator Rex Patrick is moving to refer an alleged Setka threat against CA to the privileges committee. Patrick has also sent the matter to the Australian Federal Police.

The reference to the privileges committee will sail through. The ALP, which is battling to expel Setka, will support it as enthusiastically as the government. The Greens are considering their position before the Thursday vote.

Read more: Albanese one step closer in long march towards John Setka's expulsion

Setka attracts condemnation across the spectrum. But so far his critics have found actually landing outcomes - whether expulsion from the ALP or resignation from his union office - elusive.

The latest chapter in the Setka story arose from a union meeting where his inflammatory comments were recorded, and then leaked to Nine media. (While Setka rages about leaks against him out of these meetings, it doesn't seem to occur to him to avoid making comments worth leaking.)

On the recording, Setka is heard recounting what he'd told senator Jacqui Lambie - who had cooked him a roast and tried to persuade him to quit his union job - when they discussed the government's Restoring Integrity bill. This legislation contains sweeping powers to deal with recalcitrant unions and officials.

"If them fucking other crossbenchers want to fucking vote for this Integrity bill, let 'em fucking vote for it but they will wear the consequences of it. Because [with] the money we are saving by not giving to the ALP, we will start a fucking campaign," he said.

Setka went on to say that when Nick Xenophon had voted for the Australian Building and Construction Commission "we launched a campaign in South Australia ... we fucking destroyed that fucker".

Centre Alliance is the old Nick Xenophon Team rebadged.

If the Centre Alliance senators voted for this bill, Setka said, in 20 years time someone would point to them in the street, saying they had "fucked up" not just construction workers but all workers in Australia. It is this part of the Setka tirade on which Patrick is basing the case about his making a threat.

On radio on Wednesday Setka claimed there was nothing to hear in all this. Perfectly normal. "It's called campaigning. It has actually been around for a few hundred years.

"There has been no threat made. We don't go around threatening politicians or senators," he said.

As it happens, Patrick has some first hand knowledge of what had happened to Xenophon. He says he was witness to two CFMEU workers "accosting" Xenophon at a Perth airport lounge around the time of the ABCC legislation being voted on.

Setka told the ABC he had "always treated people with respect" and if the crossbenchers thought differently "maybe they should toughen up a little bit because it is called campaigning and if they're not used to campaigning, maybe they are in the wrong job".

Actually, Patrick is quite tough. Certainly he is willing to take on those he thinks are seeking to challenge or stand over him in any way.

A while ago, Patrick made a big fuss when Mike Pezzullo, secretary of the Home Affairs department, rang him. Pezzullo had taken exception to Patrick's comment about him in the wake of the police raid on a News Corp journalist's home. The senator said Pezzullo hated media scrutiny. Patrick accused Pezzullo of trying to silence him by the phone call (an accusation Pezzullo strongly rejected).

On the Labor front, Setka's ALP membership is already suspended and Anthony Albanese is adamant that he will have him expelled from the party. But getting him out of the party hasn't been so easy. Setka launched court action. He lost, but he's appealing the decision.

Now that he will be defending himself against the claims in the privileges committee, he's become a one-man lawyers' picnic.

He has also turned into the best friend the Morrison government could have in its effort to get through that Ensuring Integrity legislation.

Although the legislation would not apply to Setka's past action, his current carryings-on give, from the government's point of view, an ideal backdrop to its argument against parts of the union movement, most notably the CFMMEU.

The government needs crossbench support to get the bill through the Senate. Lambie plans to vote for the legislation if Setka doesn't step down from his union role. Centre Alliance has concerns about the bill but Patrick said Setka "has done his own cause a disservice because I am now privy to exactly [what] some members of the Victorian construction industry tell me that they have to put up with when dealing with the CFMEU".

Read more: Fall-out from Setka affair could give Coalition easier passage of union bill

Setka saya he'll stay "as long as the members want me". The loyalty of his members to a man who is doing so much damage to the union movement defies reason.

Author: Michelle Grattan - Professorial Fellow, University of Canberra