The Queensland MP, a conservative populist and avowed fan of US President Donald Trump, drew up the letter to Prime Minister Malcolm Turnbull when feeling frustrated over a tense sugarcane dispute in his electorate, according to The Daily Telegraph.

Mr Christensen's threat was that he would withdraw support for the government unless a code of conduct for the sugar industry was established. He has reportedly contemplated an arrangement where he would jump to the crossbench but seek to sit in on Nationals party room meetings.

Nationals leader Barnaby Joyce said Mr Christensen "has a strong belief in the National Party and the things that we fight for".

"We are good mates. He is loyal to me," he said. "I hope and I believe that George will be loyal to his nation and stick with a good government."

Prime Minister Malcolm Turnbull told reporters: "I've never seen any indication that he is anything other than a committed member of the Coalition party room."

Defence Industry Minister Christopher Pyne labelled the story a "beat up".

"George has confirmed that he is remaining within the Coalition. He is a valued colleague, he is making a great contribution and the Coalition has had a terrific week," Mr Pyne told Channel Nine.

The News Corp report says a disillusioned Mr Christensen is "incensed" over the renewed push for same-sex marriage inside the Liberal Party and "outraged" he did not get a cabinet post. He is currently the Nationals party whip.

The Turnbull government holds a one-seat majority in the House of Representatives following the close-run 2016 election, meaning that every Coalition vote counts.

Senator Cory Bernardi recently defected from the Liberal Party to lead his new Australian Conservatives party, accusing his former colleagues of being in the "out-of-touch political class" that was "failing the people of Australia".

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