The Greens have shared internal polling that finds its statewide primary vote to be slightly above One Nation’s. Nation losing steam in Victoria? New poll points to possible shift as election nears Benita Kolovos Two things happened this week to suggest the One Nation surge in Victoria may be losing steam.

First, the opposition leader, Jess Wilson, made her first public criticism of Pauline Hanson’s party. Then, the Greens shared with Guardian Australia internal polling that shows its statewide primary vote above One Nation’s.

Internal polling should of course be treated with some caution. Conducted by the Online Research Unit between 14 and 26 October, the Greens surveyed Victorians across the state who are eligible to vote, with an effective sample size of 1,488, a margin of error of 3% and a 95% confidence level.

But its results are interesting, particularly when compared with the Newspoll published on Monday. The Greens’ polling put the two-party-preferred vote at 54–46, remarkably close to Newspoll’s result, which showed the Coalition leading Labor by 55–45.

There was also little difference between the two polls on the major parties and the Greens. The Greens’ polling had the Coalition’s primary vote at 32%, against 33% in Newspoll; Labor’s at 25%, against 24%; and the Greens at 15%, against 14%.

The biggest discrepancy was One Nation. Newspoll put Hanson’s party on 20% of the primary vote, while the Greens’ polling had One Nation at 14% – a six-point difference that would represent a significant setback for the party if reflected across the state. The figures are consistent when respondents were asked about who they would vote for in the upper house.

The Greens were already feeling confident at their campaign launch earlier this month where the party’s new federal leader, David Shoebridge, spoke of a boost in membership numbers since taking over the leadership.

Shoebridge returns to Melbourne on Sunday to hold what the Victorian Greens say is “one of their biggest campaign events yet”. About 200 volunteers have signed up to door-knock every remaining house the party has yet to reach across three inner-city electorates Richmond and Melbourne, which the Greens currently hold, and Prahran, which they want to win back from the Liberals after losing it at the 2025 byelection. Victorian Greens leader Ellen Sandell in Melbourne this week.

Photograph: Con Chronis/AAP According to Greens sources, the polling has them confident about retaining their three seats, and winning Prahran and Northcote – currently held by Labor on a margin of just 0.2%. They also say they are in serious contention in Pascoe Vale and Footscray. Map showing the margin by which incumbent parties hold inner city Melbourne seats.

In the upper house, the party estimates it could be enough to secure at least one seat in every region, as well as a second seat in northern metropolitan. By the Greens’ assessment, One Nation could secure a similar number of seats.

Among disaffected Labor sources, there is a view that the Greens are picking up the party’s more progressive supporters, who believe the “new direction” Ben Carroll has promised as premier is taking their party too far towards the centre-right.

They point to Carroll’s increasingly fractured relationship with the unions his decision to delay legislation guaranteeing a right to work from home and the government’s subsequent failure to pass the laws when they returned to parliament. They also cite Labor’s decision to match Coalition election commitments, including Jack’s Law, which allows police to wand people for weapons without a warrant.

This week Carroll also announced plans to ban patients from hospitals and force them to pay for their ambulance transport if they abuse or threaten healthcare workers, which raised eyebrows among some in caucus who have concerns that vulnerable Victorians could be denied healthcare as a result.

One Labor MP pointed to Carroll’s speech at a Victorian Chamber of Commerce and Industry pre-election event on Tuesday, where he declared he was a “pro business” and “fiscally conservative” as also causing some unease among more progressive types.

At the same event, Wilson made her first direct public criticism of Hanson’s party, saying: “One Nation doesn’t even plan on submitting a single policy for costing.”Her comments were followed by a report in The Australian newspaper on Wednesday that the Parliamentary Budget Office had costed One Nation’s baby bonus and children’s sport voucher scheme at $688.7m – about $553m more than the $136m the party had announced at a press conference last week One Nation was forced to acknowledge an error in its figures, admitting to The Australian that the $136m figure was an annual cost, rather than the cost over the forward estimates. Even on that basis, though, the party’s figure would still fall $144.7m short of the PBO estimate.

One Nation has a member in the Victorian parliament’s upper house, Rikkie-Lee Tyrrell, meaning the party could access the PBO to cost its policies.

But this particular costing was commissioned by the Victorian Liberal party It speaks to a growing confidence within the Liberal party to take on One Nation directly – likely because it is more optimistic of forming a majority government after recent polls. But its approach is telling – the Liberals are questioning One Nation’s economic credentials and the credibility of its policies, rather than resorting to name-calling or political point-scoring. Which brings us to the leaders’ debate.

Throughout the week, Wilson has rebuffed calls to participate in a three-way debate with Carroll and One Nation’s Victorian leader, Warren Pickering.

Two media outlets had requested that all three leaders take part, but Wilson has maintained that the traditional debate format is a “one-on-one” contest between the leaders of the “two parties that [can] govern after this election”.

On Tuesday, she even quipped that if Pickering was invited, so should the Victorian Greens leader, Ellen Sandell.

Now, it looks like exactly that is happening, with Wilson taking to social media on Saturday to confirm she would be taking part in a “people’s forum”, where the audience asks the questions, on 17 November that also includes Sandell on the lineup alongside Carroll and Pickering. Sandell says her polling proves she deserves to be there.

“We’re seeing a huge surge in support for the Greens right now because people are fed up with the major parties and they want real change,” she says.

“It’s about time we had the Greens on the debate stage to actually have someone up there who represents the people, not just big donors.”Benita Kolovos is Guardian Australia’s Victorian state correspondent