Minister 'not thinking' about free car at birthday bash

A senior minister under fire over a boozy surprise birthday lunch that ended her best friend's career has dismissed suggestions she should also quit.

NSW Housing Minister Rose Jackson fronted the press the day after Transport Minister Jo Haylen resigned her portfolio over her misuse of a taxpayer-funded chauffeured van on the Australia Day long weekend to visit a winery.

Ms Jackson says in hindsight she "probably should have said something" when she saw the van parked outside Ms Haylen's holiday home 130 kilometres from Sydney.

"But at the time, I didn't think about it because I was excited by (my) surprise birthday ... lunch," she told reporters during a tense press conference on Wednesday.

"I was just a passenger."

The car travelled to a Hunter Valley winery for a three-hour lunch, before dropping the ministers, their husbands and two friends back at the holiday home near Lake Macquarie, and returning to Sydney to end the 446km trip.

Premier Chris Minns argued the egregious behaviour was within the rules but outside public expectations.

Ms Jackson was adamant her own use of government cars met "the pub test" as she defended occasionally using the ministerial perk with her kids or to get to the airport.

"I'm really confident that it all meets the public expectation of a busy person who's trying to grab a phone call, (receive) private, confidential briefings and get the kids around."

The opposition derided the explanation as a "nervous giggle excuse", telling the minister she "turned 40, not 14".

"She was too 'excited' to think about it ... a fair-minded and reasonable person would not accept this," Opposition Leader Mark Speakman said.

Despite the scandal forcing Labor into its first major cabinet reshuffle, the search for further indiscretions amongst cabinet colleagues had already ended, Mr Minns confirmed on Wednesday.

He dismissed the merit of a wide-scale audit, instead taking ministers at their word they had used their taxpayer funded cars appropriately.

"The existing rules that are in place are so liberal that an audit would find that it was all within the rules," Mr Minns said.

The premier said he had rewritten - in "bright red lines" - rules that banned the use of ministerial drivers for exclusively private purposes.

Private use is now only permitted if it's incidental to the discharge of a minister's official duties.

Ms Haylen's disrespect to the ministerial driver was both uncharacteristic for her and his wider cabinet, which the premier said had a culture of "humility and gratitude".

"I don't want (the public) thinking that we're running around like Louis the 14th's court being waited on hand and foot by people," he said.

While Ms Haylen will refund taxpayers the $750 cost of the January 25 trip, she won't be forced to cover other private trips including one to the Blue Mountains, west of Sydney.

The outgoing transport minister said on Tuesday it "kills her" that people might think she hadn't acted with integrity.

Her departure will force the Labor government's first major ministerial reshuffle since coming to power in March 2023.

Roads Minister John Graham will take on the vacant transport portfolio in the interim, with early speculation he will keep it.

But he could be forced to shed responsibilities for arts, the night-time economy and special minister for state.