Coalition MPs risk a voter backlash if Malcolm Turnbull was cut down as prime minister before the next election, with nearly three quarters of Australians wanting an end to the leadership instability plaguing Canberra.

The final Fairfax-Ipsos poll for 2017 has found 71 per cent of voters think elected prime ministers should govern for a full term, rather than being dumped prior to an election. In a finding that will give nervous Liberal and Nationals MPs pause for thought, support for allowing a prime minister to serve a full-term leaps to 80 per cent among Coalition voters.

The poll also shows Labor has maintained its commanding 53 per cent to 47 per cent lead over the Coalition on a two-party preferred basis - the same result as surveys conducted in September and May.

If that result was repeated on election day, there would be a 3.4 per cent swing away from the Turnbull government which, if uniform, would trigger a loss of about 16 Coalition seats and hand power to Labor.