Nationals senator Matt Canavan said he was proud of the Coalition's industrial relations reforms, which have threatened to destroy One Nation's chances of winning the seat of Hunter.
"There is obviously disagreement [within One Nation] about how to tackle the issue of casualisation, but for that to lead to someone threatening to leave the party just seems to me like there must be more to it that we don't know about," Mr Canavan, who will lead a three-day tour of the Hunter starting on Monday, said.
"We are proud that we passed laws to give people in the black coal industry the right to convert to permanent work. I just don't see how it would be reasonable to make businesses back-pay people who have been casual and who have gotten a casual loading in the past - you get paid more if you are casual. You can't then come back and say I want my leave entitlements too; that would be a complete trashing of the principle of the same pay for the same work."
Fellow Nationals senators Bridget McKenzie and Perin Davey will join Senator Canavan for the party's second pitch to the region's voters in five months.
"We are taking it [the Hunter] very seriously; it's one of the reasons we are back," he said.
The trio will visit the Port of Newcastle on Monday, Rix's Creek coal mine and a meatworks on Tuesday.
"The fundamental purpose [of our visit] is to protect the jobs that make the Hunter Region a great place to live," he said.
"The Hunter Region is a beautiful place but if you don't have a job between Monday and Friday you can't do anything on Saturday and Sunday. It all starts with protecting the industries that create the jobs. That is why we take no shame in supporting the coal industry. We think there are growth opportunities for Australian coal in a world that continues to demand high quality. Newcastle has the best coal in the world and I say that as a Queenslander."
Senator Canavan said an announcement on the federal National Party's candidate in the seat of Hunter was 'imminent'.
"There is an interested person. I'll leave it to the party to make an announcement but it's imminent. Watch this space." he said.