The government will seek to thread the needle this week when it introduces legislation for a national anti-corruption bill – as the Coalition and crossbench MPs express totally different reservations about supporting it.

The government plans to introduce the bill if it is approved after being considered by caucus on Tuesday as part of a package of legislation, including for the Senate committee that will oversee it.

The main bill will allow for retrospective investigations into a range of wrongdoing and will not rule out investigations into so-called pork barrelling.

Whether such matters are investigated or become the subject of public hearings will depend on the interpretation of a federal commissioner, who will determine whether alleged behaviour rises to a legislative test of serious or systemic (not both) corruption.

The government has been seeking support on either side of the aisle and has been consulting the crossbench and the Coalition in the hope it can secure universal backing for the bill.

Competing demands

To do so will require it to balance competing demands.

Crossbench MPs who are pushing for a body with a scope for investigating third parties denies it will be too wide for practical application.

Conversely shadow finance minister Jane Hume said the Coalition supported anti-corruption measures in principle, but implied they had tipped the balance too far against those being investigated by some state bodies.

“We’ve always said we supported the introduction of a federal ICAC,” she told the ABC’s Insiders.

“This is really important legislation to get right, because if you get it wrong it has dire consequences.

“Will there be procedural fairness and natural justice? Will hearings be in public or will they be in private? When will they be one or the other?

“Will legal fees be subsidised? Because what we’ve seen in other states and other jurisdictions is when an ICAC goes wrong, well, it actually affects people’s reputations, it affects their employability, people have taken their lives because of a poorly functioning ICAC and we do not want to see that happen again.”

Senator Jane Hume said not getting the details right could discourage people from public life. Photo: ABC

Senator Hume said failing to get such details right could deter good people from careers in public life.

“We want the best and the brightest to join,” she said.

“But if the risk to your professional reputation, if the risk to your bank balance, if the risk to your life and your livelihood is there just because you can politicise a corruption charge, well, why would anybody enter public life?”

If the Coalition does not support the bill, the government will need support from crossbench MPs to secure its passage.

No deal, Coalition

The crossbench is yet to see the bill.

The Greens are pushing for the provisions of any integrity body to include third parties, or individuals not on the government payroll.

MPs, staff, public servants and contractors will be in scope. But the Greens are pushing for the commissions to include all beneficiaries of government decisions, such as the mining industry.

They are warning against seeking support from the Coalition to pass the bill.

“If Labor cuts a deal with Peter Dutton it will be proof they were never serious about stamping out corruption and ending the rotten bipartisan culture of favours for mates,” Greens Senator David Shoebridge said.

“The only deal on offer from the Coalition is a Morrison-lite anti-corruption commission, and if Labor takes that path they will have surrendered integrity within six months of taking office.”

A spokeswoman for Attorney-General Mark Dreyfus said the National Anti-Corruption Commission would investigate “serious or systemic corruption of or by a public official”.

“The commission will be tasked with investigating serious or systemic corruption,” Mr Dreyfus said.

“The commission will be independent and the government will not be instructing the commission on what it can and cannot investigate.”

Prime Minister Anthony Albanese will be attending Shinzo Abe’s funeral in Japan on Monday but aims to be back for the likely introduction of the bill on Wednesday.