I pledge to make PM a success: Dutton

The man some think could replace Malcolm Turnbull as leader has told his Liberal colleagues to do everything they can to make the government a success.

"I serve in his cabinet because I believe in him as leader," Immigration Minister Peter Dutton when quizzed about his leadership aspirations by reporters in Canberra on Thursday.

"I want all my colleagues to do everything within their power to make sure the government succeeds, the prime minister succeeds - that is what I pledge myself to."

Mr Dutton laughed off suggestions a morning walk with cabinet colleague Mathias Corman was a sign of leadership tensions inside the government.

"I go to the gym. I am sorry it doesn't show but I do exercise a fair bit. And he, like me, wants to lose a fair bit of weight," he said.

"I am not sure if that accords with your conspiracy theory but two middle-age blokes trying to lose weight, I am not sure you can speculate on that."

Senator Corman was equally dismissive, tweeting: "Secret talks? Is this a joke? Only in Canberra will some interpret a longstanding early morning (public) exercise routine as a conspiracy."