MORNINGTON PENINSULA — Liberal candidate Anthony Marsh won the Nepean state by-election on the Mornington Peninsula, with the Liberal Party retaining the seat it has held since the electorate's inception apart from a four-year period under Labor. With close to 80% of votes counted, Marsh received 38.5% of the primary vote and 63.4% of the two-candidate count.

The by-election was triggered by the sudden resignation of Sam Groth, who was deputy leader of the Victorian Liberal Party at the time he stepped down. The Labor Party did not field a candidate.

One Nation candidate Darren Hercus received 24.7% of the primary vote, while independent Tracee Hutchison received 21.3%. The Victorian Electoral Commission initially ran the two-candidate count as a race between the Liberals and Hutchison, who was in second place early in the count before slipping behind Hercus. The Liberal Party experienced a swing of close to 10% against it on the primary vote.

"So glad I could bring it home for you tonight. This is the honour of my life to be standing here as the next member for Nepean," Marsh said on election night. He did not live in the electorate and was unable to vote for himself in the by-election, having served as mayor in the area three times over the past five years. "I'll be on the ground each and every single day fighting for the people of Nepean as we lead into one of the most important state elections that we've seen," he said.

Pauline Hanson campaigned alongside Hercus during the contest but was absent on polling day. "We've had a few Liberal voters come over to us for frustrations they've been feeling with their own party," Hercus said of the campaign. Referring to Hanson's drawing power with voters, he said, "People will vote for her rather than me."

Benjamin Moffitt, a senior politics lecturer at Monash University, assessed the stakes for the major party ahead of the result. "If they even do somewhat well in Nepean, that's a real problem for the Liberal party," Moffitt said.

The electorate of Nepean includes the postcodes of Sorrento, Portsea and Flinders, and the area of Capel Sound, formerly known as Rosebud West. The Mornington Peninsula is officially part of metropolitan Melbourne. Public transport and a planned revamp of Rosebud hospital are key local issues in the area.