Voters in five federal electorates – Braddon, Fremantle, Longman, Mayo and Perth - will return to the polls on Saturday to replace the five members of parliament who lost their seats in the citizenship crisis earlier this year.

But most interest will be on the Queensland seat of Longman, centred on the transport hub city of Caboolture, where Bill Shorten faces the real prospect of becoming the first opposition leader in almost 100 years to cede a seat back to the government in a by-election.

If that happens, and polling this week suggests it’s more than likely, then the impact will be felt right across the country, including here in Bathurst.

Because losing Longman could well be the last straw for Labor MPs who have been working behind the scenes to secure numbers for a leadership tilt by popular the popular Member for Grayndler, Anthony Albanese.

Mr Shorten knows it, Prime Minister Malcolm Turnbull knows it and every would-be candidate right across the country knows it.

Because if Mr Shorten is rolled by his colleagues, all the interest will then be on just how long Mr Turnbull would give Mr Albanese to find his feet in the top job before calling a general election.

He has previously said he wants to take the government to full term which would mean an election in the middle of next year, but turmoil in the Labor ranks could tempt him to go early.

At the same time, Mr Turnbull would be wary of the polling boost that comes with a change of leadership for a party, so he would have to get his timing right to jump on that wave as it starts to fall.

It’s a fine balancing act that ensures the political focus becomes more on internal machinations than on running the country, and just the sort of scenario that makes fixed terms appealing.

Of course, the people of Longman could avoid all that intrigue by simply returning Labor candidate Susan Lamb and givng Mr Shorten some breathing space.

So vote well, people of Longman, and be very aware of the power you’ve been given.

Because you’re not just voting for your local MP, you could also be voting for a new leader of the opposition and a potential PM.