Labor has accused Bridget McKenzie of backdating approvals for a controversial community sporting grants program to make it appear to have been decided a week before the election was called.
The then-sport minister sent approvals for the final round of the $100 million grants program to Sport Australia - the body in charge of the money - about 20 minutes after parliament was formally dissolved on April 11.
However, the brief was dated a week earlier.
The auditor-general has criticised Senator McKenzie's office for running a grants assessment process biased towards coalition-held and target seats.
Nearly three-quarters of the projects given money were not recommended by Sport Australia.
Labor's Senate leader Penny Wong quizzed officials from the prime minister's department on Monday about their knowledge of an email Senator McKenzie sent Scott Morrison on April 10, the day before the election was called.
The auditor has characterised that email as Senator McKenzie telling her boss which grants she "intended to approve".
Senator Wong said to the committee hearing in Canberra, "the clear inference" from the evidence and time frame was that the grants approval "was backdated" after Senator McKenzie consulted the prime minister.
"I put to you that Senator McKenzie backdated the brief," she said.
Finance Minister Mathias Cormann said that was an outrageous allegation.
"I've got no reason to doubt the evidence of Sport Australia that the brief approving those projects was dated 4 April," he said.
After the lunch break, he told the committee he had spoken to Senator McKenzie.
"(She) unequivocally confirmed to me that the brief approving the third round of projects in the sports grants program ... was signed by her on the 4 April. No ifs, no buts."
Senator Cormann said he hadn't raised questions about the email - the subject of intense parliamentary and media scrutiny last week - with the prime minister or his staff.
Department deputy secretary Stephanie Foster said she had seen the April 4 brief and it used the phrase that a decision "has been made".
She later clarified she had not seen the email Senator McKenzie sent to Mr Morrison and nor was it in the department's system because it was not a formal letter.
Earlier, Senator Wong accused Senator Cormann of being part of a cover-up, after a dispute over whether relevant department officials were available for questioning.
"Have some credibility, it is utterly corrupt," she said.
"I am asserting the Liberal Party's approach on this is corrupt."
Senator Cormann described the accusation as a "ridiculous assertion".
He said it was not unusual for a minister and the prime minister's office to communicate "around the announcement arrangements, around launch events" for grants or other programs.
A Senate inquiry into the so-called sports rorts heard last week there were 136 emails sent between Senator McKenzie and Mr Morrison's office about the scheme.
It also heard Sport Australia twice warned the minister about the risks of her approach.
Australian Associated Press