Libs narrowly ahead in Herbert

The last undecided seat from the federal election is turning into a cliffhanger.

In the latest counting for the north Queensland seat of Herbert, sitting LNP MP Ewen Jones is just 34 votes ahead of Labor challenger Cathy O'Toole.

The day after the election, Herbert appeared a certain ALP gain but Mr Jones has relentlessly closed the gap, thanks to the flow of postal votes his way.

A win in Herbert would give the government 77 seats in the 150-seat lower house, one more than the majority the government needs to pass disputed legislation.

Seventy-seven seats would enable the coalition to reappoint Victorian MP Tony Smith as House of Representatives speaker and still have a majority on the floor.

Counting will end on Friday, the deadline for arrival of the last postal votes.