Malcolm Turnbull insists he won't resign at the end of the year after Barnaby Joyce said he should consider stepping down if polls don't improve by Christmas.
After the prime minister matched the 30 Newspoll loss test he set for Tony Abbott before the 2015 leadership coup, Mr Joyce weighed in.
He said Mr Turnbull should do the "honourable thing" and resign if the coalition remained in an election-losing position at the end of 2018.
"Towards the end (of the year) near Christmas you'd have to start asking those around you what do they believe is the proper course of action from that point forward," Mr Joyce told Sky News on Monday.
Mr Turnbull said his former deputy was free to provide advice.
"I can assure you I will be leading the Liberal-National coalition to the next election which will be held in the first half of next year," Mr Turnbull told reporters in Brisbane.
Asked about the Mr Joyce's comments, Mr Abbott said it was "Barnaby's take on things".
"The point I make is that you would expect the government with six months to go before an election to have a sense that it can win," he told 3AW radio on Tuesday.
Deputy Liberal leader Julie Bishop rejected Mr Joyce's argument, saying talk about leadership tensions was hypothetical.
"I don't agree with Barnaby Joyce. The prime minister will lead us to the next election," she told ABC radio.
After the Newspoll was published on Monday, Treasurer Scott Morrison, Home Affairs Minister Peter Dutton and Energy Minister Josh Frydenberg all openly said they would be keen on the top job in future.
Asked about her colleagues' ambitions, Ms Bishop said they were "presumably ... speaking about their future ambitions".
"They've all said that Malcolm Turnbull will lead us to the next election so I think we need to look at their comments in that context," she said.
Ms Bishop ducked questions about whether she too aspired to be prime minister one day, saying her priority was the jobs she holds now.
Nationals deputy leader Bridget McKenzie also disagreed with Mr Joyce, insisting the Turnbull government was delivering.
Asked if he has forgiven Mr Turnbull for deposing him in 2015, Mr Abbott accepted politics was a rough business.
"Some of my colleagues, a majority in the party room as it turned out, thought that they would have a better chance based on opinion polls of winning the election under Malcolm than under me," he said.
He acknowledged opinion polls had never been very kind to him, but said he had won 25 seats off Labor.
The latest possible date for a simultaneous half-Senate and House of Representatives election is May 18, 2019.