Deputy Liberal leader and outgoing Treasurer Josh Frydenberg says it will be "difficult" but not impossible to hold onto his inner-Melbourne seat of Kooyong, where independent Monique Ryan appears likely to claim victory.
Mr Frydenberg, who has been tipped as a natural successor to outgoing Prime Minister Scott Morrison, has faced strong competition from Dr Ryan, one of the so-called "teal" independents.
On Saturday night, Dr Ryan was ahead in Kooyong, and the ABC election computer projected Mr Frydenberg would lose.
Addressing his supporters, Mr Frydenberg acknowledged the task ahead of him.
"While it's mathematically possible that we win in Kooyong, it's definitely difficult," he said.
"They say in politics that politicians are the volunteers and our families are the conscripts, and a truer word couldn't have been said.
"Because the fact is, I have been supported every single day of this job by the most remarkable partner in life, in my wife Amie."
He told the crowd his prep-aged son had told him earlier that day: "A girl at school says her mum is more important than you."
"Amie replied, 'Blake, all mums are important!'," Mr Frydenberg said.
"Amie has been the most extraordinary mum, and maybe after tonight I get a bit more time to try and be the most extraordinary dad."
In traditional Liberal heartland in Melbourne's leafy inner-east, Kooyong takes in suburbs such as Kew, Hawthorn, Balwyn and Camberwell.
The seat has been held by the conservative side of politics since its creation at Federation, boasting former prime minister Robert Menzies and former Liberal leader Andrew Peacock as previous local members.
Mr Frydenberg has comfortably held the seat since 2010. Dr Ryan has been the first challenger seen as having a real chance to oust the Liberal Party.
Mr Frydenberg is the Liberal Party's most senior Victorian.
As the treasurer, he has played a key role in developing the federal government's support programs as Australia navigated rolling COVID-19 lockdowns over the past two years.
Independent declares 'Kooyong, our climate has changed'
Dr Ryan is a neurologist who most recently headed a department at the Royal Children's Hospital in Melbourne.
Her campaign has been funded by donations from thousands of grassroots supporters and the Climate 200 group created by businessman Simon Holmes a Court.
Dr Ryan has been running on a platform of climate action and greater integrity in federal politics and on Saturday night told her supporters "Kooyong, our climate has changed".
Dr Ryan, who said she was not making a victory speech, thanked hundreds of supporters who assisted her campaign.
"We started because we wanted action on climate change … our government wasn't listening to us, so, we've changed the government," she said.
"And that is the power of the people."
Dr Ryan has declined to say which party she would endorse in the event of a hung parliament, but has previously said she would work with whoever had the strongest policies on climate and electorate.
The contest has been highly visible, with billboards, posters and corflutes plastered around the electorate and large volunteer bases handing out flyers during the campaign.
The debate at times turned personal, with a stoush emerging earlier this month after Mr Frydenberg shared an anecdote about Dr Ryan's mother-in-law at his campaign launch.
Tensions also flared on election day, with the Liberal Party accusing Dr Ryan's campaign team of publishing posters that did not include all the necessary authorisation information.
