New South Wales Police Minister Troy Grant has pulled out of the running for the seat of Dubbo at next year's state election, admitting he has lost the energy to continue for another four years.

Speaking to the media on Thursday afternoon, Mr Grant said he could not commit to working in state politics until 2023 — the year flagged for the following state election — and would therefore not put his name forward for re-election.

"Today's decision is one that I take with a heavy heart," he said.

"This a decision that's about the best interests of my family. It's an honest decision.

"I no longer had the energy to continue for another four years.

'Son of a country copper'

Entering State Parliament in 2011, Mr Grant was minister for a number of portfolios, such as hospitality, gaming and racing, tourism, trade and investment, regional infrastructure, arts, justice and his current portfolio: police.

Then-deputy premier Troy Grant and premier Mike Baird at a meeting in 2016. ( AAP: Dean Lewins )

Most notably he was parachuted into the deputy premier role in 2014 after then-Nationals leader and deputy premier Andrew Stoner stood down, citing family commitments.

He was in the deputy premier role for more than two years, but stood down in November 2016 following the Nationals' poor showing at the Orange state by-election, which was attributed, in part, to the then greyhound racing ban and council amalgamations.

Reflecting on that decision today, Mr Grant described it as a "tough period".

"We tried to do the right thing," he said. "But we got it wrong politically. I paid an enormous price, my family paid a greater price. But we've been really blessed and I'm the sort of guy that focuses on the positives, rather than the negatives."

Describing himself as the "son of a county copper", Mr Grant said he was proud of his contribution.

"Not to only ensure the Dubbo electorate gets its fair share, but that all of country NSW prospers," he said.

"I would like to thank the great people of the Dubbo electorate for the trust they have placed in me and I look forward to continuing to work with them right up until [next year's election].

"I also extend my appreciation to many current and former colleagues, party members and staff for their support and loyalty.

"Above all, I thank my wife Toni and our children Taylor and Hamish for their love. It is their support and sacrifice that has allowed me to proudly serve NSW."

Who's his replacement?

For the National Party, Mr Grant's resignation opens the inland seat of Dubbo.

It comes as the seats of Orange and Barwon also open up for the country party, meaning three new Nationals candidates will contest the 2019 state election in those critical seats.

Orange fell in the 2016 by-election to the Shooters, Farmers and Fishers party candidate Philip Donato, with issues such as the then greyhound racing ban and council amalgamations seen as contributing factors.

"Those issues are not as hot or as hostile as they were back then," NSW Nationals chairman Bede Burke said.

"We will encourage those [National] members to get good people to put their hands up for preselection."

The seat of Dubbo is currently held by a 70 per cent margin by the Nationals.

'A tough period'

Premier Gladys Berejiklian and Deputy Premier John Barilaro thanked and commended Mr Grant for his service to NSW.

"As a former highly decorated police officer himself, Troy served in his ministerial roles with the sort of experience and insight the people of NSW expect and deserve," Mr Barilaro said.