Senators weighing up Setka police referral

Crossbench senators are weighing up referring construction union boss John Setka to police over an alleged threat made against them if they vote for a union-busting bill.

In a leaked recording reported by Nine newspapers on the weekend, Mr Setka said Centre Alliance would be aware of the damage the CFMMEU could inflict after launching a campaign against founder Nick Xenophon.

"We f***ing destroyed that f****er. That's why he's not around," he said at the meeting in Melbourne.

The Victorian secretary of the construction union also said they could expect to be abused in the street in 20 years' time if they voted for the bill, which makes it easier to deregister unions and ban officials.

"Someone is going to point the finger and say, 'There's them f***ers that voted for that Bill that f***ed up not just construction workers but all workers in Australia'. And I said [to Senator Lambie], 'They can f***ing wear that'."

Centre Alliance's Rex Patrick said his partyroom colleague Stirling Griff and independent Jacqui Lambie were considering involving police.

The senators could also refer the matter to parliament's powerful privileges committee or have Mr Setka explain himself before the Senate's employment committee.

"I dish it out a fair bit in this place so I cannot be complaining when it comes back in my direction, but the comments attributed to Mr Setka in recent reports are entirely beyond the pale," Senator Lambie told parliament on Monday.

Senator Patrick said no politician should be threatened or intimidated in relation to a vote.

"There should be zero tolerance for anyone who seeks to influence a senator's vote by way of a threat. We can't possibly leave this unattended," he told the upper house.

Senator Lambie, who has threatened to vote for the Morrison government's Ensuring Integrity bill unless Mr Setka quits, reiterated her calls for him to step down.

"My vote will never be determined by who bullies me the most," she said.

"To John, I can only appeal to whatever is left of your sense of decency and honour, and ask you consider what is plainly in the best interests of your union members."

She said she would not make further comment until the crucial crossbench bloc decided what course of action to take.

"Politics can be brutal but it should never become violent," Senator Lambie said.

Industrial Relations Minister Christian Porter said Labor and the union had failed to act against Mr Setka.

"John Setka ... is obviously in charge of their (union) anger management programs," Mr Porter told parliament.