The contest is so tight you could "flip a coin" to decide Saturday's poll, one senior state Liberal told AAP.

The MP claims the messy federal leadership coup that saw Malcolm Turnbull dumped as prime minister, combined with a local corruption scandal, has seriously eroded the party's once safe 12.9 per cent margin in Wagga.

Ms Berejiklian on Friday conceded the Liberals could be punished for focusing on themselves rather than the community over the past few months.

"What I've learned during this campaign is that the focus always has to be about the community - not about politicians, not about what we say to each other," Ms Berejiklian told reporters in Wagga.

"There is a possibility we may not hold the seat."

The coalition's primary vote has plummeted to 25 per cent, according to a recent ReachTel poll published by News Corp Australia ahead of the by-election, which was prompted by the resignation of disgraced local Liberal MP Daryl Maguire.

Running a Nationals candidate may have limited the damage following Mr Maguire's dodgy dealings, insiders say, but no coalition candidate would have been immune from the fallout of the federal leadership coup.

"Who would have foreseen the shit show in Canberra happening weeks before the Wagga by-election," the senior Liberal MP said.

The Nationals agreed not to run in the by-election to avoid a three-cornered contest but Labor candidate Dan Hayes says that's pushed some local Nats to support the main independent rather than the Liberal Party's Julie Ham.

"They're not here handing out for the Liberal candidate, the Nationals have absolutely vacated this space and some have shifted over to Joe McGirr," Mr Hayes, a local councillor, told AAP.

Dr McGirr, a local doctor and academic running as an independent, believes voters have been turned off by the Liberals' sense of entitlement and is confident they have the appetite for change.

"A lot of people are really excited today, there's a sense to make a change," he told AAP at a pre-polling booth in Wagga.

"It has been encouraging and it has been good for the seat; it energises people, it gets them thinking."

Labor leader Luke Foley argues Wagga voters have a "once-in-a-generation" opportunity to elect a non-Liberal MP in a seat that's been held by the conservative party for 60 years.

"This is the one chance the people of this electorate get, perhaps in their lifetimes, to send a very strong message to the Liberals and that's 'Stop taking us for granted'," Mr Foley told reporters.

Australian Associated Press