Fresh from its loss of government in the nation’s second most populous state last week, there are strong indications that the Liberal Party faces another blow at a byelection to be held in South Australia tomorrow.

Covering the Happy Valley and Aberfoyle Park regions of southern Adelaide, the state electorate of Fisher has been vacated by the death of Bob Such, who held the seat as a Liberal from 1989 to 2000, and then as an independent until his death on October 11.

The seat is one the Liberals would normally expect to hold, particularly in the context of a byelection held 12 years into the life of a Labor government that limped back into office in March. However, a fly has appeared in the Liberal ointment in the shape of an independent who appears set to garner support from voters in the market for a natural successor to Such.

Daniel Woodyatt is a 35-year-old lawyer at the Crown Solicitor’s office, and while he carries a certain amount of baggage as a former active ALP member, he has crucially received the public endorsement of Such’s wife.

The momentum behind Woodyatt’s campaign was illustrated by a poll in The Advertiser on Tuesday crediting him with 30% of the vote, compared with 34% for Liberal candidate Heidi Harris and 21% for Labor’s Nat Cook.

While the poll’s sample was only 400 people, any result within its 4.5% margin of error would set Woodyatt up to win the seat on Labor preferences.

For South Australia’s Liberals, a defeat in Fisher would add another disappointment to a year that has been full of them.

Liberal leader Steven Marshall would have begun the year eyeing the measurements to the drapes in the premier’s office, given the state of the polls and Labor’s recent electoral record federally and in other states.

The Liberals did indeed outpoll Labor quite comfortably when the election came around on March 15, but the distribution of its vote was such as to leave it agonisingly short of victory with 22 seats in a lower house of 47.

Even so, the re-election of Such and another independent, Geoff Brock in the Port Pirie-based seat of Frome, meant a Liberal minority government remained a theoretical possibility.

But in a cruel blow for all concerned, Such shortly announced that he was taking medical leave to receive treatment for what proved to be brain tumour. His removal from the equation greatly simplified the equation for Brock, who could only hope to create parliamentary gridlock if he granted his vote to the Liberals.

The Liberals suffered a further turn of the knife in May when former leader Martin Hamilton-Smith traded in his party badge for a position in Premier Jay Weatherill’s ministry.

This snuffed out any hopes that a byelection in Fisher — which, as the Liberals were no doubt quietly but acutely conscious, was only a matter of time — might grant the Liberals an extra seat and another opportunity to test Labor’s majority.

The context of the byelection is such that it might well be unfair to judge the Liberals’ performance according to the conventional metric, by which substantial swings to the opposition are considered par for the course.

An analysis by the Australian Parliamentary Library found that federal byelections caused by the deaths of sitting members — which have become increasingly rare over time, owing to the younger age at which politicians are embarking upon their parliamentary careers — produce swings around half the size of those caused by resignations.

The modern expectation of heavy byelection swings is thus a result of circumstances that happen not to apply on this occasion.

Furthermore, there are a number of precedents to suggest that voters faced by precariously balanced parliaments are reluctant to use their byelection vote to aggravate the situation, as they would do by delivering the opposition an extra seat in Fisher.

Another factor beyond the state Liberals’ power is the remarkable knack their federal colleagues have shown for putting spokes in the wheels at the most sensitive possible moments.

A fortnight ago it was Agriculture Minister Barnaby Joyce declaring that it wasn’t for the Nationals to lobby for the future of the SPC Ardmona cannery, which was followed a week later by a surprise loss for his party in the relevant state seat of Shepparton.

Next came the turn of the Defence Minister David Johnston who offered the view that he would not trust the Adelaide-based ASC (formerly the Australian Submarine Corporation) “to build a canoe”.

As well as causing grave offence, Johnston left South Australians to infer that their state didn’t stand much chance of securing the $30 billion contract to build the next generation of submarines for as long as the Liberal Party had any say in the matter.

If the Liberals indeed land short tomorrow, Steven Marshall will have plenty of excuses to draw on. However, as a succession of deposed leaders can attest, excuses only carry so much weight with his colleagues in the Liberal party room.