Former Liberal Prime Minister Malcolm Turnbull has appeared to come to the defence of Anthony Albanese as the opposition called the Labor leader a liar on the issue of negative gearing.

Coalition leader Peter Dutton came out swinging on Thursday, after admitting to making an election campaign “mistake” during the leaders’ debate on Wednesday night.

Ramping up his attacks on the government, Dutton accused Albanese of harbouring a “secret plan” to abolish negative gearing if he was re-elected.

“The Prime Minister is talking about abolishing negative gearing or not telling you the truth, at least about negative gearing,” Dutton claimed at a lengthy press conference on Thursday.

“[Treasurer] Jim Chalmers is an advocate for the abolition of negative gearing and he obviously is at war with Anthony Albanese.

“The Australian public cannot trust this Prime Minister because he does not tell the truth.

“That would devastate the housing industry even more than now and hasn’t this Prime Minister done enough damage to the economy already?”

Negative gearing allows investors to write off their property losses against other income, reducing their overall tax bill.

Albanese ruled out changes to negative gearing in September, saying tinkering with the tax concession could harm housing supply.

But Dutton repeated his claim that the Albanese government had commissioned Treasury modelling to abolish negative gearing.

Albanese maintains the study was independently prepared by the department.

Turnbull took to X on Thursday and revealed that “every government” examined negative gearing, including his own in which Dutton was a cabinet minister.

“It is a major tax concession and always contentious and so it is always looked at — what does it cost?” wrote Turnbull.

“What would particular changes mean in terms of revenue and housing affordability.

“There are many pages in my memoir describing the detailed consideration of negative gearing that went on in my government in which Peter Dutton was a cabinet minister.”

Turnbull said his government did “tweak the rules”, but on the big question of the cost of housing they had decided that it would not improve affordability.

“It is all a matter of supply — we need to build more dwellings.”

Earlier, Albanese had appeared tense when answering media questions, after Liberal Senator James Patterson accused him of secretly commissioning the modelling.

Albanese called Patterson an “attack dog”. He also reiterated his comments from Wednesday night’s leaders’ debate that the public service was encouraged to come up with ideas and assessments.

Leaders’ gaffes mar campaign

Meanwhile, crossbench Senator David Pocock urged leaders to think before they speak after a series of diplomatic fumbles marred the election campaign.

Dutton admitted during the debate that he made a mistake when he falsely attributed comments to the Indonesian president.

He wrongly said on Tuesday that Prabowo Subianto had made a public statement about Russia wanting to station military planes at a base in Papua.

Nationals senator Bridget McKenzie also backtracked and apologised for comments claiming Russia and China wanted Labor to win the election.

She said the Russian defence minister and Chinese president “both have made very public comments that they do not want to see Peter Dutton as the prime minister” before acknowledging she couldn’t verify those claims.

Some 12 hours later, McKenzie found herself in another tangle as she misattributed a quote from the Chinese premier to the president when defending the crux of her earlier statement.

“It’s pretty clear from President Xi’s public commentary that he finds Albo a very handsome boy, he’s been very complimentary about the Prime Minister,” she told Nine’s Today Show on Thursday.

She also repeated similar comments on ABC TV.

It was Chinese Premier Li Qiang who commented “people were saying that we have a handsome boy coming from Australia” when Prime Minister Anthony Albanese visited Beijing.

Pocock said it was prudent for politicians to ensure they had their facts straight when talking about world leaders.

“We keep hearing that we’re in really tense and delicate times when it comes to geopolitics … so you would probably expect people to really think through what they’re saying,” he said.

Labor campaign spokesman Jason Clare chastised Dutton for his statements as Coalition frontbenchers defended their leader’s about-face, saying Australians wanted a leader who would front up when they made a mistake.

“The relationship between Australia and Indonesia is critical, if this is not a disqualifying moment, I don’t know what is,” Clare told ABC radio.

Climate and energy policy tripped both leaders up in their debate, with Albanese repeatedly refusing to say when power bills would come down and Dutton side-stepping whether climate change impacted natural disasters.

“I’m not a scientist and I can’t tell you whether the temperature has risen in Thargomindah as a result of climate change,” Dutton said.

Coalition finance spokeswoman Jane Hume was forced to mop up after the comments on Thursday, saying Dutton believed in climate change and listened to the scientists.

Pocock said neither major party listened to scientists on climate change as “we would be doing a lot more if they were”.

“It’s pretty appalling to have someone who wants to be prime minister in 2025 in a country that stands to lose a lot from climate inaction, not being stronger on climate,” he said.

Albanese takes a slight lead over the opposition into the second half of the campaign as Dutton’s support drops, according to a Freshwater poll published in the Australian Financial Review.

Labor and the Coalition are tied at 50-50 in the two-party preferred vote — a 1 per cent improvement for the government since the start of the campaign — while Dutton dropped in support as preferred prime minister.

Further analysis from the pollsters indicated Labor could still finish short of a majority with 71 seats, compared to 66 seats for the Coalition under the same modelling.

Other recent polls have put Labor well ahead on a two-party preferred basis, including a lead for the government of 54.5 to 45.5 per cent in a recent Roy Morgan survey.

-with AAP