The Farrer by-election is looming as a major political humiliation for the Coalition, with One Nation in serious contention to win its first federal lower house seat.

Voters in the sprawling south-west NSW electorate headed to the polls on Saturday to replace ousted former Liberals leader Sussan Ley who had held the seat since 2001.

Farrer takes in a vast rural stretch of NSW, including Albury, Griffith and Deniliquin, and has been held by the Liberal and National parties since it was created in 1949.

The 12-candidate ballot is widely seen as a four-way race between One Nation's David Farley, independent Michelle Milthorpe, Liberal candidate Raissa Butkowski and Nationals candidate Brad Robertson.

But the real contest appears to have narrowed sharply, with recent polling suggesting Farley and Milthorpe are fighting at the front of the field.

One poll put One Nation on 30.9 per cent and Milthorpe on 30 per cent, ahead of the combined Liberal and National vote on 23.2 per cent.

Milthorpe won 20 per cent of the primary vote at the 2025 federal election and finished with 43.8 per cent after preferences, while Ley recorded 43.4 per cent of the primary vote - her worst result in Farrer since she first won the seat.

Two major firsts are looking feasible to become reality in this by-election.  

Since Labor chose not to run a candidate in the by-election this might be the first time in history that neither major political party will make the final two-candidate preferred count at a federal election.

A One Nation victory would similarly deliver Pauline Hanson her party's first ever federal lower house seat.