A Nationals source told Fairfax Media polling completed last week showed The Nationals ahead of Labor by five points after preferences.

Nationals candidate Scott Barrett is now offering $1.20 on Sportsbet to win, in from $1.45.

Country Labor candidate Bernard Fitzsimon has drifted out slightly to $4.50.

The minor parties and independents have changed the most – Shooters, Fishers and Farmers Party candidate Phil Donato is now paying $11, up from $5 a month ago, Independent Scott Munro is at $21, out from $3.50 and The Greens’ Janelle Bicknell is paying $67, out from $51. 

The polling came amid reports Nationals leader Troy Grant had declared the seat won during a cabinet meeting.

If the result comes to pass, it will still be a 15 per cent swing away from former member Andrew Gee’s victory last year.

Mr Barrett said he had not seen The Nationals’ polling but said the byelection could not be declared until Saturday night.

“Looking at the Labor polling [Nationals 39 per cent, Labor 19 per cent on the primary vote], I’m pretty happy with where we’re resting,” he said.

Mr Fitzsimon said Mr Grant had jumped the gun with his claim.

With pre-poll voting under way, the parties have locked in their how-to-vote cards.

Only Mr Fitzsimon, Ms Bicknell, Cr Munro and Mr Donato have chosen to allocate preferences, which would all eventually flow to Labor assuming voters followed the how-to-vote cards and Labor remained in the count.

Mr Barrett, Mrs Decker and independents Kevin Duffy and Ian Donald have only recommended people vote one for them.

Voters can number as many boxes as they like and following how-to-vote cards is optional.

If the boxes are not all numbered, the vote will not flow onto any unnumbered candidates.