However shadow treasurer Ryan Park has offered support for drought relief while urging the premier to spare agencies helping affected farmers and communities from cuts.

Mr Park delivered Labor's budget reply speech in parliament on Thursday as Chris Minns and Jodi McKay continue their battle for the party leadership.

It came two days after Treasurer Dominic Perrottet revealed a shrinking $802 million surplus in 2018/19 and $1 billion next financial year amid a drop in revenue and record $93 billion infrastructure spend.

"We are strongly in the black, back to back," Mr Perrottet declared on Tuesday.

But Mr Park says the government will push the state into $39 billion of debt in four years after selling public assets during a record housing boom.

"Debt as a share of the economy will be the highest since the turn of the century - more than five per cent," he told the lower house.

"The interest alone on that debt will be more than we spend employing the entire NSW Police Force."

He said the treasurer had not addressed climate change on Tuesday and the budget didn't include any measures to tackle record homelessness in NSW.

Mr Park said the government would have Labor's support for any drought relief, adding that "a state stricken by drought needs a unified parliament".

But he implored the premier against applying "efficiency dividends for any agency delivering services to drought-affected communities and farmers".

Mr Perrottet on Thursday said the government had been recognised for its "strong financial management" following the release of the 2019/20 budget.

He highlighted comments by ratings agency S&P Global, which said the state's strong financial management was "evidenced by its commitment to keep annual expense growth lower than long-term average revenue growth over the next four years".

Australian Associated Press