The Labor leader and his interim ministry will be sworn in on Tuesday to allow for formal briefings to begin, Treasurer-elect Daniel Mookhey said on Monday.

Informal contact with department bosses, including Department of Premier and Cabinet Michael Coutts-Trotter, began on Monday.

Mr Mookhey said the government wanted to fully understand matters including the northern NSW flood recovery and issues that have caused repeated delays on the state's train network.

"Equally, we are looking forward to getting the briefing on Menindee - the fish kills is a big part of our immediate priority," he told reporters on Monday.

Mr Mookhey will be the first minister in Australia to be sworn in on the Bhagavad Gita, the revered Hindu text.

Needing 47 seats to form a lower house majority, Labor remained stuck on 45 on Monday afternoon as the coalition made gains in many of the 12 seats still in doubt.

Former journalist Katelin McInerney appears likely to topple MP Gareth Ward in Kiama but Lyndal Howison's lead over Liberal Jordan Lane in Ryde has narrowed and physiotherapist Sam Boughton has slipped behind incumbent Adam Crouch in Terrigal.

Miranda MP Eleni Petinos jumped 70 votes ahead of her Labor opponent while the Greens' Kobi Shetty is likely to hold off a strong Labor challenge in Balmain.

The ABC called the Liberal-held seat of Wollondilly in favour of independent Judy Hannan.

But the Liberals were able to chalk up a win in Willoughby after votes from early voting centres helped Tim James push to a 1.9 per cent margin.

Taking in National victories, the coalition have clearly won 26 seats, are likely to take Winston Hills and Upper Hunter and are ahead in six more contests."

The election featured a swing of about six per cent to Labor, dwarfed by the 16 per cent swing against the party when it lost government in 2011.

"It's taken Labor three elections to recover from the drubbing in 2011," ABC chief election analyst Antony Green said.

As the Liberal leadership shakes out, another name bowed out of the race as Dominic Perrottet's replacement after the premier announced he would step aside during his concession speech.

Having seen off a teal challenge in beachside Manly, moderate MP James Griffin on Monday confirmed he would not attempt to become opposition leader.

"I'm looking forward to focusing on Manly and I will help whoever we vote in as leader," he told AAP.

Former treasurer Matt Kean had been expected to contest the leadership but ruled himself out on Sunday, saying he wanted to "hang out and be a dad" to his three-year-old son.

Other potential candidates include former attorney-general Mark Speakman, outgoing enterprise, investment and trade minister Alister Henskens and former planning minister Anthony Roberts.

The recriminations over the coalition's loss continued on Monday but one outgoing experienced minister called for a reality check.

David Elliot said the Liberal Party shouldn't gnash teeth after "12 cracking years" in government.

But the party did need to better define itself, pointing to Penrith, Camden and Wollondilly, where substantial One Nation primary votes cost the Liberal incumbents.

One Nation experienced small swings in those seats, having backed up from a strong showing in 2019.

"One Nation didn't get the high vote that some were saying but they certainly cost us seats in western Sydney," Mr Elliot told 2GB.

In the upper house, early forecasts suggest Labor will win eight seats, the coalition six, the Greens two with one spot for each for One Nation, Legalise Cannabis, the Liberal Democrats and Shooters Fishers and Farmers parties.

The battle for the 21st and final seat is between Animal Justice Party's Alison Waters and the seventh coalition candidate, Rachel Merton.

Australian Associated Press