Byelections are not just important in the obvious sense of their results, but also for the confidence of political players.

On Saturday, Labor and Bill Shorten face a major test in the Melbourne seat of Batman – which is traditionally Labor but with the Greens now threatening the ALP’s hold.

A Labor loss would be a blow to the morale of the opposition. It would also open some debate within the party about Shorten’s performance and what should be done to combat the Greens at the next election.

On the other hand, if the ALP’s Ged Kearney came home victorious, Labor would be well placed to put the heat on Malcolm Turnbull if – as is expected – the prime minister loses his 30th Newspoll in a few weeks.

We went to Batman in the final days of the campaign and spoke to Kearney and the Greens candidate Alex Bhathal, as well as former deputy prime minister Brian Howe, who once held the seat, and former Greens leader Bob Brown.

Michelle Grattan does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.