David Farley swept to victory for One Nation in Farrer on Saturday night, ending the Coalition's 77-year reign in the federal seat.
It was One Nation's first federal lower-house election victory since the party was founded by Senator Pauline Hanson in 1997.
The One Nation leader put no limit on her goals for the next federal election.
"It's not up to me to put a number on that... it's up to the people of Australia," she told Sky News on Sunday from Albury.
Former Nationals leader turned One Nation MP Barnaby Joyce also suggested the political earthquake would spread.
Farrer comprises more than 126,560 sq km and fills out the south-west corner of NSW.
The race, which became a two-way competition between a minor party and an independent, signals a broader shift in voting away from the major parties.
Electoral analyst and blogger Ben Raue said independent candidate Michelle Milthorpe was unable to offset Mr Farley's strong results in regional and rural booths by running up the score in the major centre of Albury and its surrounds.
"One Nation has dominated the right-wing bloc," he told AAP.
Monash University politics lecturer Benjamin Moffitt said the result was not unexpected with the ongoing rise of One Nation, although the decisiveness of the Liberals' drubbing came as a surprise.
"One Nation has clearly built legitimacy, at least for now," he said.
"It will now be okay after South Australia and this election to vote One Nation. The dam wall has burst."
Dr Moffitt said the swing to One Nation reflected a broader global trend toward right-wing populist parties, pointing to the dominance of Reform in UK council elections.
The by-election was triggered when long-time MP Sussan Ley resigned after being ousted as Liberal leader by Angus Taylor in February.
Support for the Coalition crumbled, down to 12 per cent of the primary vote for the Liberals and less than 10 per cent for the Nationals.
Ms Ley secured more than 43 per cent of the primary vote when she retained the seat at the May 2025 election.
Shadow treasurer Tim Wilson did not rule out forming a minority government with One Nation to defeat Labor at the next election.
"It all comes down to what Australians put up," he said.
"I want to stop the Albanese government from continuing to wreck Australia."
Deputy Liberal leader Jane Hume said trust with voters had been broken after the Coalition split twice and it would take time to rebuild.
But Ms Ley said it would be wrong to attribute the result to the Coalition ruptures and parroted Mr Taylor's catchcry of ‘’change or die’’, which he deployed after February's leadership spill.
"Three months later, the result in Farrer demonstrates that statement to be far truer today than it ever was then," Ms Ley said.
Treasurer Jim Chalmers described the result as a "bloodbath" and said it showed the Coalition would have to join One Nation to compete.
Labor did not contest the by-election.
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