NSW Premier Dominic Perrottet has called his opponent Chris Minns to concede defeat as Labor sails toward a majority government.

Labor is tipped to gain the 47 seats it needs to govern in its own right, with the ABC predicting as many as 50 seats going to the ALP.

An early two-party preferred swing of about 6.4 per cent led to decisive calls by analysts on Saturday night.

“I can confidently say, the Labor Party will form government, we do not know whether it will be a majority or minority, but the swings are now consistent,” ABC election analyst Antony Green said just under  two hours after polling stations closed.

“The Coalition is struggling to get above 27 at this stage. That is not going to turn around, Labor will have more seats in parliament.”

Liberal leader Dominic Perrottet, who became premier 18 months ago after Gladys Berejiklian quit amid an ICAC probe, had sought a fourth term for the Coalition.

Treasurer Matt Kean blamed the Liberals’ woes on the “12-year factor”.

“I think it’s the 12-year factor. No Coalition government has ever won a fourth term in NSW,” Mr Kean told the ABC.

“You accumulate barnacles.”

As cheers erupted at ALP headquarters, Penny Sharpe confirmed she would be environment minister, Daniel Mookhey would be treasurer and transport would go to Jo Haylen.

At 43, Mr Minns will be the youngest leader to win a NSW election since a 40-year-old Nick Greiner took government in 1988.

Labor Party officials had earlier been cautious about talking up victory, having formed government from opposition only twice since World War II – in 1976 under Neville Wran and 1995 led by Bob Carr.

Their caution was shared by Labor’s transport spokeswoman Ms Haylen, who said Labor had “a big mountain to climb”.

“We’ve previously only won six and three to form government from opposition,” she told the Seven Network.

But Labor veteran Ms Sharpe said the party, all but destroyed in 2011, was more determined and united under leader Mr Minns.

“I’ve been in the Labor Party since 19 years old, in parliament for 17 years and I’ve never seen the united and focused purpose that Chris has built,” Ms Sharpe told the ABC.

An election eve Newspoll showed Labor was clear favourite to form government.

Labor led the Coalition 54.5 to 45.5 on a two-party preferred basis, a swing of 6.5 per cent on the 2019 results.

Prime Minister Anthony Albanese was doing his best earlier on Saturday to help turn the Liberal seat of Ryde red.

While Mr Albanese was complimentary of Premier Dominic Perrottet, he pointed to the retirement of key ministers – including local MP Victor Dominello – as proof the government was at the end of its life.

“It’s time for a change of government. And I hope that happens today.”

-with AAP