Mr Joyce said all parties had no control over the public thoughts of retired politicians and drew a comparison between Mr Jasper and former Labor leader Mark Latham.

"It's like us going back to the Labor Party and making them responsible for Mark Latham and everything Mark Latham says," Mr Joyce said on the campaign trail in northern NSW.

"We have people who have formerly been strongly involved in the Liberal Party and holding responsible as an endorsement everything the Liberal  Party says.

"Once you leave politics, I know this comes as a shock, you're a free agent, as much as we'd like at times to rein them in."

Mr Jasper lobbed a grenade into the Indi battleground by urging voters to back the National Party candidate Marty Corboy and then Ms McGowan, who he endorsed three years ago.

Mrs Mirabella denied a report stating she contacted senior Coalition figures in the wake of Mr Jasper's comments on Thursday.

"After Mr Jasper's support for Cathy McGowan, who votes with the Greens' 72 per cent of the time in contested votes, there was no need to make any call to any senior Coalition person," she said.

Mr Corboy has again distanced himself from Mr Jasper.

"People are not interested in political insider games," he said.

"My focus has been and always will be the people of Indi.

"I will work right up until July 2 and hopefully beyond."

Meanwhile, CrownBet is offering odds on the number of primary votes Mrs Mirabella will attract with between 25,000 and 29,999 the favoured option at $2.75 ahead of 20,000 to 24,999 second pick at $3.

Mrs Mirabella winning between 30,000 and 34,999 primary votes is rated a $3.50 chance.

The former member attracted 39,785 votes in the 2013 poll.