ABC election analyst Antony Green has called the Wagga Wagga by-election for independent candidate Dr Joe McGirr.

Speaking on ABC News on Sunday night, Green said he felt safe calling Saturday's by-election, slightly more than 24 hours after the polls closed.

"He is a certain winner," Green said.

The race for the seat, which had been vacated by disgraced Liberal MP Daryl Maguire, became a two-man battle between Labor's Dan Hayes and Dr McGirr after the Liberals were hit with a 29 per cent swing against them.

But Green said Labor scrutineer figures suggested the gap was too big too close.

"They won't catch him," he said. "We have no idea how many votes [he will win by] but the gap won't narrow."

"We were certain last night that the Liberals wouldn't hold on to the seat, but the only unknown was who would win . . . but we are now sure that Joe McGirr will win Wagga Wagga."

Dr McGirr, a medical doctor and academic at the University of Notre Dame Australia, has lived in central Wagga since 1991 and only decided to run for the seat three weeks ago.

Dr Joe's campaign van. He says the Liberals felt they "owned" the seat. ( Facebook )

Dr McGirr said Green's call was "very exciting" but he wanted to wait for the official count before claiming the seat.

"I'm very humbled by that news, it's a great honour," he said.

"But we're keeping a lid on it."

Dr McGirr said he decided to run as he felt the Liberals believed they "owned the seat".

"And that concerned me, that sort of talk felt as though they were taking the seat for granted," he said. "So a couple people approached me, and that was motivation [to run]."

During the campaign Dr McGirr ruled out joining the Nationals following reports local branch members had supported his campaign.

Dr McGirr also ran for the Wagga Wagga seat at the 2011 state election, managing a significant swing to him at the time on the back of a campaign for a new hospital in the region.

A strong message

Responding to the result on Sunday, New South Wales Premier Gladys Berejiklian said she regretted the fact that voters had "lost trust" in the way they were being represented.

NSW Premier Gladys Berejiklian said the people of the Wagga "no longer trust the way in which they were being represented" ( AAP: Perry Duffin )

"I don't think any one of us could have foreseen the circumstances that occurred during the campaign," Ms Berejiklian said.

"The people of the Wagga region sent us a strong message.

"I regret that the people of the Wagga region came to the conclusion that they could no longer trust the way in which they were being represented.

"They were angry and disappointed at the actions of the former member, and I share that."

The Liberal Party has held the safe Riverina seat for about six decades since winning it in a by-election in 1957, before disgraced MP Daryl Maguire resigned after seeking payment over a property deal.

"There's an underlying distrust of how Government works," Ms Berejiklian said.

"And I need to restore that and demonstrate to the community that we're here for them."

Federal lib spill factored in, says Premier

Ms Berejiklian also blamed the Federal Government's leadership spill for loss of voter trust.

The ABC's Antony Green has called the Wagga by-election for Dr Joe McGirr ( ABC News )

"When you put over the top of that, what occurred at a different level of government, that certainly exacerbated what the community was already feeling, and I want to say to the community — I've heard what you had to say.

"My Government has heard what you had to say, and I also appreciate that we will redouble our efforts to deliver for you into the future," she said.

"It was very interesting in this election. People weren't raising a lot of local issues or policy issues.

"This was really about trust in the political system, trust in politicians. And the by-election result exacerbated that. It was not an election where people were worried about a particular local issue."

Nats could have won, says party member

Wagga-based Nationals MLC Wes Fang said he believed his party could have won if they ran a candidate.

Mr Fang was critical of the Liberal campaign and said the Coalition will have to work hard to win back the trust of voters.

"They've run a city strategy in a country seat and it hasn't played well, that's pretty obvious from the result today (Sunday)," he said.

"It would have been good for us to highlight the wins that we've actually received for the electorate, and there's been many, we just don't communicate those wins very often."