Australia's most marginal seat of Corangamite is looking on track for a solid Liberal victory, candidate Sarah Henderson says.

Liberal Ms Henderson leads Labor incumbent Darren Cheeseman 53 to 46 per cent on a two-party preferred basis, with 75 per cent of the vote counted.

Ms Henderson is shy of claiming victory for the Victorian southwest coast seat but admits things are looking positive.

"We just want to take it one step at a time but certainly it's looking very positive that we will have a solid victory in Corangamite," she told AAP on Sunday.

"My feeling was that it would be very close and I'm very thrilled with the result that has been achieved to date."

So far, the results show a four per cent swing to the Liberals on a two-party preferred basis.

Ms Henderson says a quarter of the electorate voted early and when pre-poll and postal votes come through, the result will be more certain.

She says a strong grassroots campaign, a pledge to fix the Great Ocean Road and disenchantment with Labor played a significant part in the outcome.

"The biggest message I received when I was travelling around all the polling booths yesterday was we need change," she said.

Mr Cheeseman held the seat by a wafer-thin margin of 0.3 per cent.

In 2010, Ms Henderson, a former journalist, bucked the state trend when she recorded a swing towards her, but fell 800 votes short of taking the seat.