The government hopes changes released on Friday will get its "ensuring integrity" laws over the line in the Senate.

Unions have flagged a last-ditch lobbying effort to battle the laws.

The new so-called demerits scheme would also apply a threshold of $189,000 in fines to an organisation before it could be deregistered.

Industrial Relations Minister Christian Porter says the "sensible" amendments were developed in discussions with Senate crossbenchers.

"Both Centre Alliance and One Nation have engaged by suggesting and discussing amendments; their constructive engagement on the bill to address issues of relevance has been a very positive process," he said.

"The amendments circulated by the government today reflect those discussions and provide additional safeguards, whilst still ensuring the bill is able to achieve its key purpose - ensuring registered organisations and their officers finally obey the law."

Other changes include removing the minister's power to apply for deregistration, reducing the grounds for disqualification, and only applying a public interest test to union mergers if one of the organisations has a history of rule-breaking.

ACTU president Michele O'Neil said while the union movement appreciated the efforts of crossbenchers, the amendments did not stop attacks on ordinary working people.

"If the tests in these amendments, and this bill, were applied to politicians, political parties or corporate executives many would not be able to continue to hold office or run corporations," she said in a statement.

"We will now meet with the crossbench senators and ask them to only consider their final position on the bill after they have heard from and considered the views of those directly affected and experts in this area of law.

"This proposed bill will have serious implications for all Australian workers and should be treated with the utmost care."

The government needs crossbench support to pass the legislation because Labor is staunchly opposed to what it sees as an existential attack on unions.

Opposition industrial relations spokesman Tony Burke says even with the changes, the bill remains "fundamentally unfair".

"It will entrench the double standard where if a bank breaches the law 23 million times the prime minister considers it 'a matter for the board' - but three paperwork breaches could bring down an entire union without the members getting a say," he said in a statement.

"The truth is these laws will hurt ordinary workers by taking away their advocates: the organisations that fight for better wages, combat wage theft and exploitation, and keep workers safe."

The legislation is set to be debated in the upper house on Monday.

Australian Associated Press