With less than two weeks until a crucial NSW by-election, a public stoush has erupted between Deputy Premier John Barilaro and Malcolm Turnbull.
NSW National Party Leader Mr Barilaro was antagonised by the former Liberal prime minister's endorsement of an independent candidate in the 13-strong field for the Upper Hunter by-election on May 22.
On the weekend Mr Turnbull - who owns a property in the Hunter Valley - threw his support behind local farmer Kirsty O'Connell, saying she would represent the Upper Hunter "with courage, independence and vision".
"Unlike the Nationals, she will not take the community for granted," he posted on Facebook.
"They have no plan for the future other than the unconstrained destruction of the landscape with open-cut coal mining," Mr Turnbull said.
He noted that Mr Barilaro had gone on radio to denounce him as "treacherous among other epithets" and retaliated, saying, "there is not one person in NSW who has done more to destabilise and disrupt the Berejiklian government than Barilaro".
Just weeks ago Mr Barilaro applauded Mr Turnbull's recent dumping from the state's Net Zero Emissions and Clean Economy Board, after the former prime minister called for a moratorium on new coal mines in the Upper Hunter.
The by-election is a must-win for the Berejiklian government, which has been in minority after losing two MPs.
Michael Johnsen quit after being accused of rape and former sports minister John Sidoti moved to the cross bench after becoming the subject of a corruption inquiry by ICAC.
The Nationals have held the seat - in the heartland of the state's coal mining industry - for 90 years but are hanging on with a slim margin of just 2.6 per cent.
The major parties are all vigorously supporting the industry, with Labor candidate Jeff Drayton "a proud coal miner".
On Monday the NSW government matched Labor's pledge to fund a new $12 million police station for Singleton.
Mr Barilaro and Police Minister David Elliott joined Nationals candidate Dave Layzell to make the announcement, saying it would be a significant boost for the region.
Early voting in the by-election began on Monday.
Australian Associated Press