Dumped prime minister Tony Abbott says Malcolm Turnbull will have to explain why he shouldn't go if he has just two more bad Newspolls.

Mr Turnbull cited the coalition's 30 consecutive poor results in opinion polls as among the reasons he toppled Mr Abbott in 2015.

The latest Newspoll published in The Australian shows the two-party preferred vote unchanged with Labor on 53 per cent and the coalition 47 per cent.

It's the 28th time the government has been behind since the 2016 election.

"It was the prime minister who set this test and I guess if he fails the test it will be the prime minister who will have to explain why the test was right for one and not right for the other," Mr Abbott told 2GB radio on Monday.

"It will be up to him to tell us all why the test doesn't apply in his case."

Along with the bad run of Newspolls, Mr Turnbull also listed a desire to trust cabinet ministers to do their jobs and the need to provide economic leadership when he challenged in 2015.

Newspoll shows the primary vote for both parties rose by a point - within the margin of error - taking the coalition to 37 per cent and Labor to 38 per cent.

And Mr Turnbull - who witnessed the swearing-in of new Nationals ministers in Canberra on Monday - is only narrowly clinging to his preferred prime minister status, dropping nine points in a month to 37 per cent.

Labor leader Bill Shorten is the preferred prime minister for 35 per cent of people polled.

A month ago, the prime minister was 14 points ahead of Mr Shorten.

"My opposite number has chosen to define himself by opinion polls - I define myself by my values and my priorities," Mr Shorten told reporters on Monday.

The poll was taken after Barnaby Joyce resigned the Nationals leadership after revelations about his affair with his former media adviser.

Parliament's febrile atmosphere with threats from ministers to further air rumours about others' private lives is likely to also have been fresh on potential voters' minds.

"I think the last month that we've seen, February, of parliament, has turned even more Australians off politics," Mr Shorten said.

Returning Nationals minister Keith Pitt conceded it had been a messy start to the year but said his constituents weren't interested in the gossip and rumours.

"I don't work on the set of Days of Our Lives. This a serious building where serious decisions are made and we continue to be focused on that," he told Sky News.