Ms Berejiklian's decision to quit Parliament ahead of an inquiry into her conduct in relation to grants given to The Range function centre and the Riverina Conservatorium of Music has sparked turmoil within the Liberal-National coalition.

Deputy Premier John Barilaro on Monday announced his resignation as a Member of Parliament, declaring it was the right time for him to "hand the reins over" to new leadership.

The decision came just a day after veteran Liberal MP and Transport Minister Andrew Constance announced he was quitting the NSW Parliament in order to seek pre-selection for the federal seat of Gilmore.

Political experts said the Liberal Party and The Nationals should be able to win the three by-elections, however, there is a possibility the balance of power could shift to minor parties and independents like Wagga MP Joe McGirr.

Charles Sturt University politics professor Dominic O'Sullivan said the three departing MPs' seats were "very safe" but there was still a risk.

"If we get a really significant increase in COVID cases, maybe the public will react negatively and there will be an electoral backlash," he said.

Dr O'Sullivan said in order to capitalise on the unrest, Labor would need to explain "how it would do things differently"

"I think McGirr is going to have to wait for the opportunity to gain the balance of power; as we have seen, the situation can change very rapidly but as things stand right now I would expect the government to retain those three seats," Dr O'Sullivan said.

University of Sydney government and international relations senior lecturer Stewart Jackson said the by-elections created a "certain amount of danger" for the government.

"If they were to lose Monaro and Bega, they have to ask if the independents, and that includes Joe McGirr, will support the continuance of the government or will they bring the government down and put in a new one?" Dr Jackson said.

"The only way we might end up in a [general] election is if the independents said they did not trust either side."

Dr Jackson said the independents could gain more power before the by-election if they sought guarantees from the government in exchange for their support later, if needed.

In a statement on Monday, Dr McGirr said he had enjoyed working with Mr Barilaro and wished him all the best for his future.

"His support during the Black Summer bushfires and on into the recovery has been invaluable and much appreciated," Dr McGirr stated.

"Mr Barilaro worked hard for regional NSW and his efforts on the development of regional initiatives such as the special activation precincts will bring significant benefits to Wagga and the region."

Dr McGirr's statement did not address questions about whether he had discussed any by-election and balance of power issues with fellow independents, but did foreshadow future talks on support for the government.

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"Now more than ever there is a need for stable and effective government." Dr McGirr said.

"We are about to go into an immensely challenging period as the state opens up and the number of COVID-19 cases and hospitalisations increase.

"My fellow independents and I look forward to meeting with the new premier and deputy premier in due course to discuss our support going forward."

Wagga-based Nationals MLC Wes Fang said Mr Barilaro "has been a great friend" to the city. "If you were to ask any of the leaders in this region, they would all indicate that John had delivered for and listened to the people in our area," he said.

"That has given everyone the confidence to know that investments like the special activation precinct are but the start of the vision for regional NSW in this area."

NSW Treasurer Dominic Perrottet is widely tipped to replace Ms Berejiklian as premier, while Melinda Pavey and Paul Toole are possible deputy premier candidates.

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