Frank and furious assessments about the New South Wales Government's prospects in next week's Wagga Wagga by-election are not hard to find at Macquarie Street.

"We've lost it," one senior minister said, while another bemoaned: "We should have let the Nats run."

A third lamented last week's leadership spill in Canberra, saying: "The feds' stuff has killed us; I'm 80 per cent sure we've lost."

The Berejiklian Government — which lost the previously safe Nationals seat of Orange in a 2016 by-election — is facing the prospect of defeat in Wagga Wagga, which has been in Liberal hands since 1957.

Many feel the Liberal brand is, for now at least, more hindrance than help because of the fallout from events in Canberra last week.

But voters in Wagga Wagga are not only angry about the change in prime minister — they are angry about their former state MP Daryl Maguire.

Mr Maguire was forced to quit after a tape was played in a hearing at the Independent Commission Against Corruption [ICAC], revealing he sought payment of a "dividend" over a property deal.

Nats not running could ruin government's chances

Under an agreement between NSW Premier Gladys Berejiklian and Deputy Premier John Barilaro, the Nationals has decided not to run a candidate in the Wagga by-election.

Independent candidate Joe McGirr said the public felt like it was being taken for granted.

Dr McGirr, the former director of emergency medicine at Wagga Wagga Base Hospital, ran in the 2011 election and received a 30 per cent swing in the primary vote.

He did not run in the 2015 state election, but has decided to have another go on Saturday, September 8.

"They're angry because there is no three-cornered contest. If the Nats had run there would have been a choice," Dr McGirr said.

"The way it looks is a Liberal MP hasn't behaved, so out he goes and in comes another Liberal with a quick election to try to get it dealt with.

Dr Joe McGirr is running as an independent in the 2018 Wagga Wagga by-election ( Source: joemcgirrnews )

"The mess in Canberra is the icing on the cake."

Former deputy prime minister Tim Fischer echoed the voter fury.

Mr Fischer said the Coalition agreement for decades had been that both Liberal and National candidates could run in a general election or by-election when an MP retired.

He said Coalition tacticians must regret blocking a Nationals candidate, as they would have improved the Coalition's chances in Wagga greatly.

"I'm suggesting that it's a very open contest with Independent, Labor, Liberal," he said.

"What's missing is a National Party candidate. I regret that that is the case.

"Whatever the reasons, they were wrong, and I suspect we'll be proving that on Saturday week."

Liberal MPs scrambling to Wagga

The Premier conceded last week the by-election would be close, and said "we could lose the seat".

The troops have been rallied and plenty of politicians have invaded Wagga.

Ms Berejiklian has been in the city four times in August. Ministers Brad Hazzard, Anthony Roberts, Troy Grant, Mark Speakman and Adam Marshall have been there, and a slew of backbenchers have also made the trip.

But Labor is not so sure the Government could lose the seat, and believes the Premier is managing expectations so she can talk down a significant swing.

Labor candidate Dan Hayes said: "What we've seen over the last few weeks is the Premier visit a number of times and announce things that two months ago in the budget were not to be found."

In 2015, Labor did not win a single booth in Wagga, and the Liberals have held the seat for more than six decades.

Labor's hopes rest with Dr McGirr, and the party will preference him in its how-to-vote cards.

The Liberal candidate Julia Ham did not return the ABC's phone calls, but a statement from Liberal Party head office quoted her as saying: "I've been out and listening to local communities from Lockhart and Uranquinty, from Adelong, Tumut, and of course Wagga."

Liberal candidate for the Wagga Wagga by-election Julie Ham (L) with Premier Gladys Berejiklian. ( YouTube: Liberal Party NSW )

"They're telling me that what matters most to them is getting more local jobs to the region and improved local infrastructure, our health services and keeping the community safe.

"I think this by-election is a real challenge, and I have no expectations about the outcome — it will be tough. But I hope that the local community will back me on September 8 and vote Liberal, so that this community can have a strong local voice in the Berejiklian Government."

If the Liberals manage to hang on and keep the seat, all eyes will be on how big the swing is against them.

But if they lose the seat, it will be first time they will be able to assess just how much damage the leadership spill in Canberra has caused the Liberal brand.