A forfeit by the Liberal Party has made it less of an event than it might have been, but tomorrow’s dual state byelections in Newcastle nonetheless loom as an interesting test of New South Wales Labor’s regeneration in former heartland seats that were swept away in the 2011 election disaster.

Byelections have been flying thick and fast of late. Western Australian Premier Colin Barnett’s Liberals were run uncomfortably close by the Nationals in the chair-sniffer’s former seat of Vasse last Saturday. The Country Liberal Party government in the Northern Territory fared better on the same day to pick up a swing in the Labor-held seat of Casuarina. And the seats of Fisher and Davenport are soon to be up for grabs in the finely balanced South Australian parliament.

While each is diverting enough for the election watcher, their significance is limited by the fact that the governments in question have two or three years to run until they next face the polls. But with judgement day in New South Wales now little more than five months away, anything less than two emphatic wins tomorrow will be a very awkward look for Labor and its leader, John Robertson.

The byelections are a legacy of the swathe that was cut through the Liberal Party in the Hunter region and Central Coast by the Independent Commission Against Corruption’s inquiries into illegal donations from property developers, which caused the resignation of Tim Owen in the Newcastle electorate and Andrew Cornwell in its southern neighbour, Charlestown.

Against some very stiff competition, Labor’s defeats in these seats ranked among their most painful results of the 2011 election. Neither Newcastle nor Charlestown — nor the latter seat’s historical antecedents Kahibah and Waratah — had even been won by the Liberal Party before.

Nonetheless, voters in Newcastle especially had long known the value of keeping Labor on its toes. When Barrie Unsworth’s government was drummed out of office in 1988 — a defeat with many similarities to that of 2011, while not quite matching it for scale — the seat fell to an independent.

When Morris Iemma led Labor to one last election victory in 2007, the party struggled to retain Newcastle in the face of an independent challenge from the city’s then-lord mayor, John Tate, who came within 1.2% of snatching the seat from Labor candidate Jodi McKay. Tim Owen went on to unseat McKay in 2011 — with, as ICAC would later learn, underhanded assistance from McKay’s Labor colleague Joe Tripodi. One of very few people to have come out of ICAC’s proceedings looking good, McKay yesterday announced she will seek to return to parliament in the inner western Sydney seat of Strathfield.

The hope that an independent might again threaten Labor loomed large in the calculations of the Liberal Party when it made its extraordinary decision to surrender two of its own seats by declining to field candidates in the byelections — ostensibly because it wished to make an “explicit act of atonement” for the “reprehensible” conduct of its outgoing members. However, it does not appear that the various challengers who have emerged have built up a sufficient head of steam, unless they have done so under the radar of the media.

Newcastle is not a particularly strong area for the Greens, and the various independents generally appear to have run low-key campaigns. A possible exception is Newcastle independent candidate Karen Howard, who boasts a fairly impressive resume.

Clive Palmer has seen in the byelections an opportunity to boost his flagging political stocks, despite having sat out recent contests on his home turf of Queensland. He was in town yesterday spruiking Jennifer Stefanac and Suellen Wrightson, who are respectively running with his backing as independents in Newcastle and Charlestown, since the Palmer United Party is not formally registered in New South Wales.

Unfortunately for Labor, voters who aren’t of a mind to support them are spoilt for choice, with eight candidates on the ballot paper in Newcastle and nine in Charlestown. Under the compulsory preferential voting system which prevails at federal level and in most of the other states, the strongest of these performers might stand a chance of snowballing to victory from a modest base vote as the preferences of each excluded minor candidate was distributed in turn.

But with optional preferential voting in operation in New South Wales, the far greater likelihood is that anti-Labor vote will scatter and dissipate, potentially allowing Labor to win with what might, in different circumstances, be dangerously low shares of the primary vote.

It will be a very different story when the state election is held in March, when exhausting Greens preferences are likely to cause Labor to fall short in seats that might otherwise be won.