The Nationals are shaping as the first party to throw their hat in the ring for an Upper Hunter by-election capturing national interest.
Singleton mayor Sue Moore will be the frontrunner when the party of departed MP Michael Johnsen picks its candidate for the May 22 poll on Wednesday night.
Ms Moore would not comment on Sunday, but Upper Hunter shire councillor James Burns confirmed he would seek the nomination.
One Nation's national head office confirmed on Sunday that its pre-selection was in the hands of NSW upper house MP Mark Latham, the party's state leader.
Mining union official Jeff Drayton is shaping as Labor's choice, though the party is not likely to run a pre-selection vote until next week.
Shooters, Fishers and Farmers Party leader Robert Borsak confirmed to the Newcastle Herald on Sunday that SFF would direct its preferences to the ALP, a move which would enhance Labor's hopes of winning Upper Hunter for the first time.
"As we have in the last three elections where we've won seats off the Nationals, we'll need a strong flow of preferences from Labor, and obviously they'll want us to reciprocate," he said.
"Otherwise we can't win."
Labor directed preferences to the Shooters in 2019, but SFF how-to-vote cards merely suggested its supporters place the Nationals last.
Mr Borsak expected One Nation to direct preferences to the Nationals, despite Mr Latham's public condemnation of the Coalition over its climate policies.
Lee Watts, another Upper Hunter councillor, won 19 per cent of the primary vote in 2015 for the SFF and 22 per cent in 2019, six points behind Labor's Melanie Dagg.
Mr Borsak said Ms Watts had not nominated "and we're looking at some other people". He expected to name the successful nominee by the end of next week.
Mr Johnsen won 34 per cent of the primary vote and clung to a 2.4 per cent margin after preferences in 2019.
The by-election will be a first test of One Nation's popularity in the area since coalminer Stuart Bonds won 21.6 per cent of the primary vote against Labor's Joel Fitzgibbon in Hunter in the May 2019 federal election.
Mr Bonds has had a public falling-out with the party's leadership after senators Pauline Hanson and Malcolm Roberts voted with the government to pass new industrial relations legislation which could adversely affect casual mine workers.
Mr Bonds has said he is weighing up whether to stand again for the party at the upcoming federal election.
Mr Burns challenged Mr Johnsen, a first-term MP at the time, in an unprecedented pre-selection battle before the 2019 state election.