Zed Seselja has hit back at Gary Humphries after the former Liberal senator and chief minister lashed the Canberra Liberals' election campaign and the conservative forces controlling the branch in the wake of Saturday's defeat.
Mr Humphries said the party was locked in "crippling and paralysing" conservatism and Alistair Coe's stunt-filled campaign hurt its credibility.
He warned the Liberals faced another 20 years in opposition without radical change.
The conservative grip of the branch has been in the spotlight since Mr Seselja rolled Mr Humphries for his Senate spot in 2013.
Mr Humphries quit party in 2014, saying it was out of touch with the ACT community, unable to control its finances and dominated by its far right. He only recently rejoined the Canberra Liberals after stepping down from his role as a deputy president of the Administrative Appeals Tribunal.
In a statement to The Canberra Times on Monday, Mr Seselja said Mr Humphries was in no position to "credibly criticise anyone" given the party's poor election result when he was leader in 2001.
The Humphries-led Liberals secured just 31 per cent of the primary vote in 2001, compared to Labor's 41 per cent. The Liberals performed far better with Mr Seselja as leader in 2012, winning more votes than Labor.
Seselja's Liberals won eight of the 17 seats on offer at the 2012 election, but it wasn't enough to stop Labor and the Greens forming government. Mr Humphries' team won 7 seats in 2001.
Mr Humphries said the election was the Liberals' to lose and could not be blamed on the coronavirus pandemic.
Leader Alistair Coe's campaign was centred around lowering the cost of living and relied on stunts copied from Boris Johnson's general election campaign to get his message across.
He came under scrutiny for failing to explain how he would deliver ambitious promises, including freezing rates for four years.
"It was a slick campaign, it was well-funded, it was well-organised, it was very focused in its messages," Mr Humphries said.
"But at the end of the day there was a hollowness at the centre of campaign.
"It deprived the Liberal Party of credibility. It couldn't explain how it was going to pay for the promises it rolled out.
"It played down the Liberal Party's most important asset which has always been its ability to balance the books.
"At the heart of the campaign there was a pointed inability to answer questions about what they were promising."
Mr Humphries said the disciplined messaging may have worked in western Sydney or regional Queensland, but it would have never convinced engaged Canberra voters.
"The Liberal Party has been locked into a crippling, paralysing conservatism that is robbing it of any chance to speak to the aspirations and values of the Canberra community," he said.
"People were actually quite tired of the Labor government and quite happy to move to an alternative.
"But the more they looked at the Liberals, the more uncomfortable they became at the prospect of voting Liberal."
Mr Humphries said the hard right had been in control of the local division for years, systematically removing moderate Liberals from all leadership roles within the party's operations.
Mr Coe was among the most socially conservative members of the Legislative Assembly.
He has not said whether he would recontest the leadership, which is traditionally spilled after a loss.
"You would think that a leader that had lost so badly wouldn't be given another go in the leadership, but again there is also the role of the party's management committee which is effectively controlled by the right," Mr Humphries said.
"It may exert a great deal of influence to make sure he stays there."
Mr Humphries said moderates Elizabeth Lee and Jeremy Hanson were the strongest leadership contenders.
But he said a moderate leader would not be enough, rather the branch must have moderate views on the need to act on climate change, marriage equality, euthanasia, abortion and investment in transport infrastructure.
"They need to look long and hard at internal structures and the way it engages with its own moderate wing, and look at its extreme conservatism," Mr Humphries said.
The Greens were the standout performer at the election, winning at least three and possibly up to six seats. They went into the election with two members.
Ben Oquist, executive director of the progressive think tank The Australia Institute, said the loss of the modern Liberal vote was the standout of the election.
While some of the Greens' gain came at the expense of Labor, more of it came from the Liberals.
"That progressive Liberal base abandoned the Liberals in Kurrajong," he said.
"I think in a way the Liberals are aware of it - we saw it in their push for 1 million trees and green space. They had a lot of green branding in their election material.
"But the image of Alistair Coe as an ultra conservative swamped all of that."
He said it was remarkable the Labor-Greens government was able to increase its showing in Parliament despite being in power for 19 years.
"One of the things about the ACT is of course there's competition between Labor and the Greens," he said.
"But there's also a lot of cooperation between them that you don't see in other jurisdictions.
"The ACT government has the most ambitious climate emissions target in the country and they were rewarded for it."