Mr Turnbull wondered whether Mr Morrison was “out of his depth” and told a cabinet meeting in February 2016 that the leaking had to stop – a remark he aimed at his treasurer and raised again in private talks after the meeting. “I have spoken to Morrison again and again about this and it was important the cabinet see that I am putting my foot down,” Mr Turnbull wrote in his diary at the time, in an extract included in the new memoir, A Bigger Picture, to be released on Monday. “He has to be, and be seen to be, on notice. He almost offered his resignation to me afterwards but didn’t. In my study here in The Lodge we agreed to go forward but strictly on the basis that we agree on matters like this privately and then announce. No more front-running.” Malcolm Turnbull addresses the media after the party room meeting for the leadership spill in 2018. Credit:Alex Ellinghausen Mr Turnbull’s claims, and his blunt conclusion that Mr Morrison played a “double game” in the government’s leadership turmoil, come at a time when the Prime Minister is seeking national unity to counter the COVID-19 virus.

The clash about “front-running” was fundamental to the Turnbull government’s fortunes ahead of the 2016 election because the debate raised expectations for change before the cabinet rejected the reforms. At one point, Senator Cormann expressed his frustration with Mr Morrison after another leak, sending a text message to Mr Turnbull that said: “We have a treasurer problem.” Mr Turnbull writes that he preferred to work on policy in secrecy without previewing it to journalists, but his treasurer could not be contained. “Scott, however, liked to start with a firm view of the solution – or, more often, the announcement – then go in search of the problem,” Mr Turnbull writes. “Plus, he confided in journalists much more than I thought was wise.”

Mr Turnbull names editors and journalists at News Corp Australia including Simon Benson, Chris Dore and Paul Whittaker as those who gained leaks about options such as an increase in the GST in a “tax mix switch” to cut personal tax rates. “Morrison, though, unfortunately nobbled any chance of GST reform becoming a reality by front-running policy options in the media,” Mr Turnbull writes. “Time and again he’d float ideas on the front page and monitor the public reaction before determining whether it was good policy or bad policy. Prime Minister Scott Morrison has been accused of leaking to the press during Malcolm Turnbull's time as leader. Credit:Alex Ellinghausen

“The biggest problem with Scott’s preferred approach of reverse-engineering economic policy via the front pages of the tabloids was that once an idea was in the public domain, no matter how good or bad it was, you couldn’t put the genie back in the bottle.” Mr Turnbull writes that Finance Minister Mathias Cormann wanted to cut Mr Morrison out of policy talks in order to avoid details being leaked to The Daily Telegraph. “It wasn’t easy managing the pair of them as their mutual distrust grew,” he writes. In an interview ahead of the publication of the memoir, Mr Turnbull said he did not believe Mr Morrison was using the media to damage the government or undermine colleagues. "We have a treasurer problem," Mathias Cormann texted Malcolm Turnbull. Credit:Alex Ellinghausen

“I worked well with Morrison. The only substantial difficulty we had was this issue of front-running, and it was a problem that I had with him, that Cormann had with him,” Mr Turnbull said. However, he added that the “front-running” damaged the government ahead of the 2016 election, when the Coalition retained power by a single seat. Mr Turnbull also writes about Mr Morrison’s positioning on the Liberal Party leadership, including a conversation in December 2014 in which Mr Morrison said Tony Abbott would have to go as prime minister during 2015 if his performance did not improve. Loading Mr Abbott faced a spill motion the following February and was removed in September, when Mr Morrison’s allies voted against him even though Mr Morrison himself did not.