One Nation has surged further ahead of Labor in a fresh national poll as a senior Victorian Liberal quit the party to support Pauline Hanson. 

A Demos/Capital Brief survey of 1,497 voters released on Monday showed the party's primary vote on 30 per cent, ahead of Labor's on 27 per cent and the Coalition on just 18 per cent. 

Modelling based on the poll estimated One Nation could win 54 to 63 seats in the House of Representatives - falling short of victory - with Labor securing between 71 and 81. 

The party's latest positive result comes as Colleen Harkin, a former Liberal executive and the party's unsuccessful candidate for the Melbourne seat of Macnamara at the 2022 election, confirmed her resignation from the Coalition on Monday. 

Harkin, who also serves as Director of Education Programs and a Research Fellow at the Institute of Public Affairs, cited long-running concerns about the Liberal leadership and its lack of direction.

Harkin suffered a nine per cent swing against her at the last election. She also ran for Castlefield Ward in Melbourne's Bayside Council in 2024, and lost a preselection contest in the seat of Goldstein to Tim Wilson, after the Liberals reclaimed it from Teal Independent Zoe Daniel in 2025.

Speaking to Ben Fordham on Sydney's 2GB, Harkin compared her departure to ending a marriage.

'There is an element of me that feels a bit sad, it does feel like a bit of a divorce scenario,' she said.

'It was a very fine thread that I was holding on to for several years, and then, like a lot of things, it went very fast.'

Harkin said she'd lost confidence in the party's leadership and sense of purpose.

'I don't see the direction, the conviction, and all of those really important things that I see in a political party,' she said.

She confirmed she would now back One Nation, arguing the party had shown the courage missing elsewhere.

'A nation is more than just an economy, and I think One Nation has been the only party prepared to have the hard conversations,' she said.

Harkin previously served on the Victorian Liberal Party's administrative committee, the body that oversees party operations.

As reported in The Age, Victorian Liberal president Brian Loughnane, husband of Sky News host Peta Credlin, had asked Harkin to explain why she attended a One Nation fundraiser featuring former Nationals MP Barnaby Joyce on June 12. 

She was expected to face disciplinary action prior to her resignation.

In her resignation letter, Harkin made it clear she believed the party, not she, had changed. 

'I have not changed. The party has,' she wrote.

'I cannot continue to support an organisation that has lost sight of its principles, its purpose and its responsibilities to its own members. I hereby resign my membership of the Liberal Party.'

She warned her decision reflected a wider dissatisfaction in the party's base.

Resignations had been 'significant', she said, adding, 'I've had literally thousands of calls from people who say, 'I feel the same way.'

The Demos survey's modelling found the Coalition would be wiped out by a One Nation and Labor dominated contest, reduced to just four seats.