Australia Post's entire board is set to be grilled over Liberal Party links at a Senate inquiry into former boss Christine Holgate's controversial departure.
Ms Holgate says she was unlawfully stood down after it emerged she gifted four Cartier watches worth $20,000 to executives who had clinched a lucrative deal.
Chair Lucio Di Bartolomeo will make his second appearance in the past two weeks on Tuesday, this time alongside the board's directors.
Tony Nutt, who was the Liberal Party's former federal and Victorian director and worked in senior roles for John Howard, is set to come under scrutiny for his conversations with Ms Holgate after the furore.
During her explosive evidence at the last hearing, Ms Holgate said Mr Nutt made it clear Scott Morrison wanted her to stand down.
"I was told, 'Christine, you need to understand it was the prime minister'," she told parliament.
"Clearly he has a very close relationship with the prime minister, but he often was the person who would be more balanced with all political parties than the other politically appointed people."
Former Abbott government minister and Liberal senator Michael Ronaldson and former Queensland LNP president Bruce McIver are also listed to appear.
Fellow director Deidre Willmott was former WA Liberal premier Richard Court's chief of staff.
At the most recent hearing, Ms Holgate claimed director Mario D'Orazio was a personal friend of former finance minister Mathias Cormann.
She believes Jan West is the only independent board member.
Mr Di Bartolomeo has rejected Ms Holgate's accusation that he threw her under the bus to curry favour with his political masters.
"I think Christine Holgate has been treated abysmally, but I believe the board and management did the right thing by her," he told the hearing earlier in the month.
Prime Minister Scott Morrison angrily condemned her in parliament over the scandal declaring she could "go" if she didn't stand aside during an investigation.
He has refused to apologise to Ms Holgate but says he regrets any distress the "willing" nature of his rebuke during Question Time may have caused.
Four unions representing Australia Post workers will also appear at the hearing next week, along with a group representing post office franchisees supportive of Ms Holgate.