Doubt has been cast on NSW Transport Minister Jo Haylen's reason for dodging an upper house inquiry into her controversial pick for a $588,000-a-year job.
Ms Haylen has fended off criticism for weeks over her choice of former infrastructure executive and Labor staffer Josh Murray to lead the transport department.
A snap parliamentary inquiry into the appointment is to hear evidence on Thursday and Friday.
But Ms Haylen will not appear, her office said on Wednesday.
"It's parliamentary convention that neither lower house MPs nor ministers appear in upper house inquiries, with the exception of budget estimates," a spokesman for the minister told AAP.
But that excuse raised the eyebrows of Opposition Leader Mark Speakman.
He pointed to coalition ministers Brad Hazzard, David Elliott, Kevin Anderson, Melinda Pavey and former premier Mike Baird, who have faced such inquiries in the past decade.
Planning Minister Paul Scully faced an inquiry into legislation in June.
"It's not a legitimate excuse," Mr Speakman told reporters.
"She keeps deflecting and obfuscating.
"She keeps saying 'I've made all the declarations I have to make'. Well, what are those declarations?"
Opposition transport spokeswoman Natalie Ward said MPs wanted to understand the process for hiring Mr Murray, who went from being under-qualified and a risk in the eyes of recruiters to "being catapulted into a half-million dollar job".
Mr Murray, a former Laing O'Rourke executive and chief of staff to Labor premier Morris Iemma, began his tenure two weeks ago as questions were raised over his recruitment.
Documents provided to parliament showed recruiters aired concerns about his experience but later interviewed him at the suggestion of Ms Haylen's staff.
Speaking notes prepared for the minister later revealed Mr Murray and his wife had donated $750 to the minister's election campaign by buying tickets to a fundraiser dinner.
Ms Haylen on Tuesday said it was "absurd" to connect the tickets with the transport appointment and denied any wrongdoing, standing by her secretary as the right person for the job.
Premier Chris Minns backed Mr Murray and his minister, denying the ministerial code of conduct had been breached.
The inquiry beginning Thursday will also examine the pandemic-time appointment of Nationals federal secretary Emma Watts as NSW Cross-Border Assistant Commissioner.
