The Coalition government has dipped to its lowest primary vote under Malcolm Turnbull’s prime ministership, the latest Newspoll for The Australian shows.

The poll delivered some sobering news for Mr Turnbull, dropping below 40 per cent for the first time – lower than when he replaced Tony Abbott  as PM.

The Coalition fell three points in the past fortnight to 38 per cent, and is down four points since the election 12 weeks ago.

Labor has also taken a two-party-preferred lead of 52 per cent over the Coalition’s 48 per cent – its biggest lead since Mr Turnbull took power.

However, Mr Turnbull remains the preferred prime minister over Labor’s Bill Shorten, despite only a third of voters being satisfied with his performance and more than half dissatisfied.

Outside of Julia Gillard’s post-election fall, Mr Turnbull’s decline has been the quickest by a re-elected government in the poll’s 32-year history.

According to the poll, Mr Shorten still lacks personal appeal. Photo: Getty

The Coalition’s worst result since the change of leader last September came after serious backlash against Mr Turnbull’s plebiscite on marriage equality.

The policy, taken to the election, has seen Turnbull’s net satisfaction rating plummet to minus 23 points, a deterioration of four points in the past fortnight.

It’s a 61-point decline since his 38-point peak in November last year.

Prime Minister Turnbull sees the plebiscite legislation as an election promise he intends to keep, despite acknowledging the reality of a Parliament in which he lacks the numbers.