Labor is in danger of falling victim to a shock loss in the historic seat of Melbourne Ports, the Greens and the Liberal Party say.

The ALP's Michael Danby has been considered on track to retain the seat, but as the count goes on the Greens are becoming more confident their candidate Steph Hodgins-May can leapfrog Mr Danby into second place on the primary vote count and force a run-off with Liberal Owen Guest.

About 30 per cent of the vote is still to be counted in the seat, with an unusually high number of postal votes and absentees yet to decide the result.