Ms Berejiklian told reporters during a visit to Singleton on Wednesday that she was well aware of the challenge facing Nationals hopeful David Layzell, saying there had been swings against governments in every by-election in NSW in the past decade.

"The Deputy Premier and myself need him on our team to have a strong and stable government and we need him to help us keep doing the job we are doing," she said.

But voters should not expect any large spending announcements from the government in the lead-up to the May 22 poll.

Ms Berejiklian said voters should consider the government's track record of investment in roads infrastructure, schools and health services in the region.

"I think communities see through that big cash splash, I think communities just want to know can they trust you, what's your track record, what have you done, can you be assured of providing that stability - that local support into the future," she said.

"The biggest marker of future success or future support is what's happened in the past."

Shadow Minister for the Hunter Clayton Barr said he was surprised there appeared to be no plans for major spending announcements before voters make their decision.

"At the very least, there's a lot of concern about the design of the Singleton Bypass and Labor will be saying more about that later in the week," Mr Barr said.

"Typically, if you want to compete and contest a by-election, you normally have to be saying to the community 'here's something we can do for you'.

"Let's not forget this government has been in power for 10 years, so fundamentally anything not already delivered to this community has not been a priority for this government."

Deputy Premier John Barilaro, who was also in Singleton, said the by-election was not about "coal versus every other industry".

"This is about what happens here, and has happened here, for decades - where people co-exist, where industries co-exist, understanding the value in all those industries," he said.

Ms Berejiklian said there was a need to support traditional energy as well as to invest in new forms.

"It's all about jobs - we want to make sure we keep industries going. We want to make sure, though, we're not left behind in terms of new technology, that's a healthy balance to have," she said.

"The balance we have across the state in terms of our energy policy is pretty much the balance the Upper Hunter has in managing very different uses of land - but all important - whether it's agriculture or equine or mining or whatever else."

The by-election was scheduled after Nationals MP Michael Johnsen resigned last month following allegations of sexual assault - which Mr Johnsen denies.

The government held a one-seat majority in the lower house before Mr Johnsen's resignation, meaning the by-election puts the Coalition at risk of having to form a minority government.

The Premier's visit to Singleton came on the same day that former Dungog mayor Tracy Norman announced she would stand as an Independent.

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