The Senate crossbench has lined up in a bloc against Nationals deputy leader Bridget McKenzie over her handling of $100 million of sports grants, leaving the minister certain to face an inquiry when parliament resumes in February.
One Nation Senator Pauline Hanson accused Senator McKenzie of using a $100 million sports grant program as a "slush fund" in a pork barrelling exercise at the last election.
"I don't think she's up to doing the job," Senator Hanson said.
Independent Senator Jacqui Lambie said Senator McKenzie's actions were "shocking".
Centre Alliance Senator Rex Patrick said the serious questions raised by auditor Grant Hehir in a report this week should be investigated by a federal corruption commission, but in the absence of such a body he would support a Senate inquiry.
Senator McKenzie brushed off the prospect, saying "the Senate will do as it will always do".
Nationals leader Michael McCormack is standing by his deputy, and on Friday, former party leader Barnaby Joyce did the same.
"If people do things that are illegal, that's one issue. If they do something as ministerial discretion, that's another issue," he said. "If we only ever do what bureaucrats tell us, we don't need ministers."
The auditor found that Senator McKenzie defied departmental rankings and assessments when she allocated $100 million to sports groups. The money was disproportionately awarded to marginal seats and sets being targeted by the Coalition in the election, with Senator McKenzie's office drawing up a spreadsheet that colour-coded seats according to the party that held them.
Senator McKenzie's office argues that it analysed the grants in that manner because she was sensitive to allegations of pork barrelling and wanted the allocation to be fair.
Senator Joyce said there was always tension between bureaucrats and ministers.
"And sometimes when bureaucrats don't get their decision they get very angry. But bureaucrats are not elected by the people. Politicians are."
Also on Friday, more footage emerged of Coalition candidates handing over-sized cheques to local sports groups in the last election, announcing Commonwealth money, despite being candidates, not MPs.
The Nationals' candidate for Gilmore on the South Coast Katrina Hodgkinson paired up with Senator McKenzie on April 11 last year, the day the election was announced, to spruik a $475,000 grant for local netball courts. A couple of weeks later, Ms Hodgkinson posed with a giant novelty cheque, while denying it was an actual cheque.
"It's not a cheque, I'm very conscious of the Georgina Downer stuff," Ms Hodgkinson told the ABC at the time. "It's a sign. Nothing more than that. It's got no signature."
She was referring to Ms Downer, a Liberal candidate at the time, being photographed two months earlier handing over a novelty cheque for $127,373 to the Yankalilla Bowling Club near Adelaide. That stunt sparked the audit into the sports grants program - with the final report released this week.
Neither Ms Downer nor Ms Hodgkinson were elected.
Lower House Independent Zali Steggall said Senator McKenzie's use of the grants in marginal electorates was "disgusting".
"It shows her complete lack of moral compass," Ms Steggall told the ABC.
Labor Leader Anthony Albanese said Senator McKenzie's position was untenable, after she had used taxpayers' money as though it was party funding in the election campaign.
"Georgina Downer, who was a candidate, not a member of parliament, was handed over an oversized cheque as if she was responsible for the grant and as if that was her money," he said.
"She wasn't even a member of parliament. You had circumstances whereby Graham Perrett who assisted a local soccer club in his electorate got a $135,000 grant. It was announced by the Liberal candidate for Morton. This is quite extraordinary and unprecedented."
Prime Minister Scott Morrison has declined to comment.
Dr Mark Rolfe, a UNSW researcher who is focused on Australian politics and leadership, said Senator McKenzie probably should resign in order to restore trust in politics.
"In the long run, given the overall distrust in politics these days which is always in the background and is now at a heightened level, I think she should go, although government supporters would say that is wrong and opposition supporters would say that's right," Dr Rolfe said.
However, he said the idea of ministerial accountability was an "archaic ideal, conceived at the height of the British empire" and the idea of Westminster responsibility was a weapon oppositions have used to "bash" ministers and prime ministers ever since.