Voters aren't getting behind either of the major parties, with their primary votes both dropping in the Newspoll published in The Australian on Monday.

Mr Turnbull's personal preference rating rose two percentage points to 48 per cent, with Mr Shorten dropping two points to 29 per cent in the last fortnight.

It is the biggest gulf between the leaders since May 2016.

But federal Labor continues to lead the coalition on a two-party preferred basis 51 per cent to 49 per cent - unchanged since last month's poll.

Primary support for both major parties fell by a percentage point, with the coalition now on 38 per cent and Labor on 36 per cent.

The Greens had 10 per cent support, and One Nation seven per cent.

Labor frontbencher Ed Husic said the personal success ratings of each leader wasn't the real story of the polls.

"What are we at? Thirty-six Newspolls where they're behind," he told Sky News on Monday.

"Even though Malcolm Turnbull has the ratings that he has, that's not translating to benefits for the government."

The poll contacted 1644 voters around the country from July 12 to 15, as the government addressed controversial changes to the GST and efforts to cut power bills.

The government has been unable to draw level with Labor since just after the 2016 election when Mr Turnbull won government with a tiny majority.

But Labor and the Liberals are fighting in two close by-elections in Queensland and Tasmania that could point to Mr Turnbull or Mr Shorten's electoral futures.

Australian Associated Press