NSW upper house results hang in the balance

In the legislative council, 21 of 42 seats were up for election.

With almost 60 per cent of total votes counted, Labor is tipped to win eight of those seats, with the coalition heading for six, the Greens two, and One Nation just one.

Election analyst Kevin Bonham said the Animal Justice Party (AJP) and the coalition were battling for a final seat, with the minor party just ahead.

"If the last seat goes to the conservatives it will be far more difficult to get legislation through," he said.

Legalise Cannabis leader Jeremy Buckingham was confident he could be elected to parliament.

"We're cautiously optimistic we can secure a spot," the former Greens upper house MP said.

The Greens and One Nation are vying to increase representation on the crossbench.

A record number of postal votes are yet to be processed, with postal voters generally more Liberal-leaning and preference flows historically left-leaning.

The AJP's chances of retaining the seat it won in 2015 - which would secure a left majority - are looking tight, election analyst Ben Raue said.

"Legalise Cannabis, Liberal Democrats and the Shooters are clearly in front, with Animal Justice in a close contest with the coalition for the final seat," he said.

Mr Raue said if the parties of the left - including Labor, the Greens, Legalise Cannabis and the AJP - won 12 seats, the votes would produce a progressive majority.

There's a chance four minor left members could be elected with the Greens and Animal Justice winning three between them, he said.

"That would probably involve Legalise Cannabis winning a seat in part by pulling in votes that would otherwise be right-wing votes, while the Greens and AJP win three between them."

Parties get one seat for every 4.5 per cent of the vote they poll, with the remaining votes and preference flows deciding the final few seats.

Australian Associated Press