Four months after losing the leadership spill he instigated, Peter Dutton has broken his silence with an extraordinary spray at Malcolm Turnbull.

Calling the deposed prime minister incompetent and indecisive, the home affairs minister told Brisbane’s Sunday Mail that Turnbull had brought about his own downfall through his lack of political nous.

“Malcolm had a plan to become prime minister but no plan to be prime minister,” Dutton told the paper.

He also criticised the former leader for actions he saw as undermining the Morrison government.

“I am the first to defend the legacy of the Turnbull government,” Dutton said. “Malcolm was strong on economic management, borders and national security, but Malcolm will trash his own legacy if he believes his position is strengthened by seeing us lose under Scott [Morrison].”

He accused Turnbull of not supporting the Liberal party’s candidate in his old seat of Wentworth.

“Walking away from Wentworth and not working to have Dave Sharma elected was worse than any behaviour we saw even under [former Labor prime minister Kevin] Rudd.”

Dutton insisted he was not a stalking horse for the former party leader Tony Abbott. “The suggestion I was acting under Tony’s direction is another fairytale. I had been clear with Tony very early on I would not be his stalking horse.”

He said Turnbull’s poor management had lost the Libs 15 seats in the 2016 election, leaving the government “with a one-seat majority which just made the parliament unmanageable. We were paralysed.”

He said Turnbull didn’t have the former Liberal prime minister John Howard’s touch, judgment or ability to deliver a message.

“We went from three-word slogans under Tony [Abbott] to 3,000 under Malcolm and our achievements weren’t effectively communicated as a result,” he told the paper.

“Countless opportunities to strengthen the government or nail Shorten passed us by because Malcolm couldn’t make a decision.

“Malcolm is charming and affable but he doesn’t have a political bone in his body and it’s not a criticism, but without political judgment you can’t survive in politics and he didn’t.”

The Morrison government did not want to comment on Sunday.