Labor's chances have been boosted ahead of the New South Wales election after the Opposition struck a preference deal with the Greens.

Both parties are fierce opponents of the Coalition Government's plan to raise money for infrastructure through electricity privatisation.

The deal they reached would involve the Greens preferencing Labor ahead of the Coalition in 25 key Lower House seats.

They include Nationals-held seats on the north coast, where coal seam gas is a key issue, and in Strathfield where Jodi McKay is trying to unseat Liberal MP Charles Casuscelli.

But the seats of Balmain and Newtown, where the Greens are hoping to beat Labor, were excluded from the deal.

In the Upper House, Labor agreed to direct preferences to Greens candidates above the line on the ballot paper and directly after its own candidates.

The Greens refused to preference Labor at the last election, citing corruption issues and the former Labor government's sale of "GenTrader contracts" for rights to purchase power station output.

Upper House Greens MP John Kaye said the situation was different ahead of the March 28 vote.

"This is about saying if you're going to have a choice between Labor and the Coalition, then Labor is better," he said.

"They're better on wires and poles privatisation.

"They're better on TAFE, although they're not there yet.

"They're better on community services."

Dr Kaye said Labor was still "spectacularly" conflicted on fossil fuels, but its promised ban on coal seam gas activity on the north coast was a step forward.

Shadow Treasurer Michael Daley said Labor entered into the deal with the sole intention to "stop Mike Baird's bad plan to sell our electricity network".

"We thought doing a deal with the Greens would give us the best chance of getting as many seats as possible and we'll use that power to stop the sale of the electricity network."

Mr Daley said the party was looking for any advantage it could get.