'The mood has turned': Prized seat of Higgins on a knife-edge as Liberal vote heads south

The Liberal Party is sandbagging one of its most-prized seats amid growing fears that a backlash fuelled by women and young voters could deliver it to Labor for the first time in history.

The government holds the affluent inner-Melbourne seat of Higgins on a margin of 7.4 per cent, but both major parties say the retirement of sitting MP Kelly O'Dwyer, an influx of young residents and concerns about leadership instability and climate change have dragged the Liberal Party's primary vote below 50 per cent, putting it at risk of a shock loss.

Internal opposition polling recently placed the Coalition just ahead of Labor by about 51 to 49 per cent on a two-party preferred basis - a sharp fall from the healthy 58-42 per cent margin Ms O'Dwyer secured at the 2016 election.

Ms O'Dwyer, the Jobs and Industrial Relations Minister who took over the seat from Peter Costello, is using her profile and connections to support the campaign of Liberal candidate Katie Allen. The Liberal Party has also had access to the $500,000 war chest the cabinet minister and leading moderate amassed through recent fundraising.

Labor ran dead during the 2016 election, allowing the Greens to finish second. But in a sign of confidence it has a shot in 2019, Labor dumped its previous endorsed candidate in March and replaced him with high-profile barrister and former Law Council of Australia president Fiona McLeod, igniting a three-cornered contest between Labor, the Liberals, and the Greens' Jason Ball.

Ms McLeod will introduce Mr Shorten at a rally on Sunday and had shadowed the leader whenever he has campaigned in Melbourne.

Katie Allen and Kelly O'Dwyer campaign on a pre-poll booth in Higgins on Saturday.Credit: Joe Armao

Asked on Saturday whether he could win Higgins - which includes Melbourne's richest suburb of Toorak - Mr Shorten replied: "Something is going on in Victoria. People don't want more of the same with the government."

To have a chance of victory, Labor would need to come second on first preferences and the Liberal primary vote would need to fall from 52 per cent to below 45.

Liberal sources said "the mood has turned" in the electorate over the last two months. They were also struck by how many early voters - particularly those in their late 30s and 40s - had made up their minds and respectfully told volunteers they liked Ms O'Dwyer and Dr Allen but could not vote Liberal, citing the party's approach to women, climate change and the dumping of Malcolm Turnbull.

While enrolment statistics show an 11.6 per cent increase in the number of voters aged 70 or older in Higgins since the 2016 election, there has also been sizeable increase in the number of voters aged below 40.

The number of voters aged 18-19 increased by 13.1 per cent over the past three years, driven by the same-sex marriage plebiscite. There are nearly 600 extra voters aged between 20-24, and 860 extra between 40-44.

Ms Allen, a paediatrician, contested the Greens-held seat of Prahran at the November state election but was caught up in a whopping swing against the Liberals in affluent suburbs and fell short. State Labor recorded double-digit swings in some of the state seats in and around Higgins.

Ms O'Dwyer has strongly backed her replacement in a series of paid Facebook ads targeting voters.

"She's been caring for our community but now she will be that strong voice for us in Canberra," Ms O'Dwyer says in the ad.

Jason Ball is contesting his second election in Higgins for the Greens.Credit: Eddie Jim

Mr Ball said the Greens had run a strong ground campaign for many months and Labor was playing catch-up.

"It's great they are finally paying attention to the seat, but my estimate is it may be too little too late," he said.

"I have been hearing today - and ever since voting started - that people are saying climate change is their number-one issue, and Labor and the Liberals are both not doing anywhere near enough on that."

In addition to Higgins, the opposition believes it had a chance in the Liberal-held seats of Deakin and La Trobe and is confident it will win Corangamite, Dunkley and Chisholm.