The fate of Deputy Nationals Leader Bridget McKenzie could come to a head this weekend, as newspaper reports unearthed further revelations into the so-called $100 million sports rorts scandal.

Prime Minister Scott Morrison has asked his head of department Philip Gaetjens to investigate whether any part of Senator McKenzie’s handling of the $100 million Community Sport Infrastructure Program breached ministerial standards.

Mr Morrison is expected to hear from Department of Prime Minister and Cabinet secretary as soon as Sunday.

An auditor-general report found the program favoured coalition marginal and targeted seats before last year’s federal election.

The audit found in the third round of the program, 73 per cent of projects given funding were not recommended by Sport Australia.

The Weekend Australian reports two of Mr Morrison’s senior staffers were involved in handling funding applications under the grants program before presenting them to Senator McKenzie when she was sports minister prior to the last year’s federal election.

Mr Morrison has rejected suggestions that funding allocations originated from his office.

Nine newspapers also reported that Senator McKenzie signed off on more that $1 million in grants for shooting clubs and associations, potentially opening her up to further allegation of conflicts of interest.

Senator McKenzie, a keen shooter herself, has repeatedly refused to step down from her leadership role in the Nationals party and from the government front bench as agriculture minister.

Mr Gaetjens was given the additional task of looking at whether Senator McKenzie breached rules in regard to her non-declaration of the membership of a Victorian gun club which received $36,000 from the program.

The minister has argued she did not need to declare the membership as it was a gift provided to her in January 2019 and round two funding from the program became available in December 2018.

And, as the gift was valued at less than $300, it did not meet the threshold for declaration, she said.

Nationals Leader and deputy prime minister Michael McCormack has defended his deputy and called out his colleagues for speaking anonymously to the media and positioning themselves to replace Senator McKenzie.

Labor argues Senator McKenzie has breached three ministerial standards: observing fairness in making official decisions; using taxpayer resources “through the lawful and disinterested exercise of the statutory and other powers available to their office”; and declaring and registering any personal interests.

If the minister is sacked, it is likely to trigger instability in the coalition government.

-AAP