New South Wales Deputy Premier and National Party leader Troy Grant has been given an ultimatum to reverse the Government's greyhound racing ban or face a leadership spill.

The ABC has been told senior National MPs, with support from others within the party, have told Troy Grant something must be done to change the Government's position before the Orange by-election on November 12.

The group of Nationals want the Government to reverse the shutdown and keep the greyhound racing industry open, albeit a smaller industry, reducing 34 tracks down to 16.

The 16 tracks would be known as centres of excellence, with quality control from industry and government.

There would be a cap on breeding and jail terms for anyone using live baiting.

The pressure to reverse comes as one MP said "we're at war internally".

Smaller industry with better oversight: senior National MPs

It has been three months since Mr Grant and Premier Mike Baird announced the greyhound racing industry would be shut down from July next year.

When the legislation passed in State Parliament, three National members crossed the floor and a number of others spoke out against it.

But now, National Party MPs have told the ABC they need to act now to save the Government and National Party-held seats across the state.

One said: "It's gone on way too long," adding "to go back now most could probably be forgiven, but not to admit you made a mistake shows poor leadership".

Twenty-one of the 34 greyhound racing tracks in NSW fall in regional areas.

Party members leaving in protest, ABC told

National MPs have suffered the biggest backlash from the ban.

The ABC has been told dozens of National Party members have resigned from branches.

"This will cost Troy dearly at the next election and a lot of others in Regional seats, this is totally against Nat principles," a Nationals member said of Mr Grant's decision to support a shutdown.

"There were plenty of other ways to clean up the Industry without completely closing it down."

The sentiment has been echoed through National Party heartland.

Grant denies 'leadership ultimatum'

When questioned, Mr Grant said he had not been approached by any senior National MPs to change his position on shutting down the industry.

"Ministers [Niall] Blair and [John] Barilaro can answer for themselves, but neither of them have asked me to reverse the ban," the Deputy Leader said.

NSW Primary Industries Minister Niall Blair said Cabinet had made its decision.

"I'm not buying into that speculation," he said.

"The Government has made a decision in relation to the greyhounds ... we're now waiting for the implementation taskforce report and until we get that there's not much else to add."

Mr Barilaro has declined to comment.

If the Nationals do formally withdraw their support for the greyhound racing ban, it puts the Premier in a very difficult position.

MrBaird has been a big advocate for shutting the industry down and stamping out animal cruelty.

He has also been the subject of huge criticism over this decision.

Either way a Nationals backflip would force the Premier into a very uncomfortable corner. The Nationals partyroom will meet again in two weeks.