John Robertson, NSW Opposition Leader since the slaughter of Labor at the March 2011 election, is about to face the biggest test of his uninspiring leadership.

He must win two byelections by emphatic margins on October 25 to validate his leadership as Labor prepares for the next state election on March 28, 2015. The byelections in Newcastle and the neighbouring seat of Charlestown are in the heartland of “rusted-on” Labor voters. However, both seats fell to the Liberals at the last election due to voter dissatisfaction with Labor’s 16-year incumbency and a succession of scandals in which one Hunter MP, Milton Orkopoulos, was jailed for child sex and drug offences.

The byelections were called last month when war hero Tim Owen (Newcastle) and Dr Andrew Cornwell (Charlestown) resigned after revelations at the Independent Commission Against Corruption that they had received cash donations from developer Jeff McCloy when he was Newcastle’s lord mayor.

The byelections fall in circumstances that could not be more providential for Labor. Premier Mike Baird insisted that Liberal candidates should not contest the two seats, fearing that the swing against his party would be as high as 25% or more. He figured that such devastating losses would crush party morale and expose Liberal candidates to “copy-cat” results in western Sydney at the state election in five months.

According to common logic, with Liberals not contesting, the byelections should produce a welcome result for Labor. Two extra MPs would take the party’s representation in the Legislative Assembly to 23 while the Coalition’s majority would fall by two.

However, when Robertson launched the campaign of Tim Crakanthorp, a Newcastle City councillor, he made a pledge that seemed to be borrowed from the script of Rob Sitch’s ABC series Utopia. He promised to build a “world-class” convention and exhibition centre “if Labor wins the March state election”.

He admitted that the same proposal had been floated by Jodi McKay, the Labor MP who lost the Newcastle seat at the 2011 election after her campaign was allegedly sabotaged by fellow MPs Joe Tripodi and Eric Roozendaal.

Robertson’s promise has been ridiculed as “pie in the sky”, a potential white elephant and infrastructure that Newcastle doesn’t necessarily need. Everyone I’ve spoken to thinks the exercise — far from collecting votes — has backfired.

The NSW Greens are the only other serious contenders. They are contesting both seats with high-profile community candidates, and they are relying on the region’s deep-seated disillusion with both major parties.

Environmental engineer and university teacher Michael Osborne, the Greens’ candidate for Newcastle, told Crikey that voters’ concerns were “trust” and “corruption”. Newcastle has the largest Green membership of any city in Australia, he said, and the campaign team had engaged in a systematic door-knocking campaign across the electorate.

This is the same strategy that brought Greens deputy leader Adam Bandt his second victory in the federal seat of Melbourne in September 2013.

In Charlestown, Greens candidate Jane Oakley, secretary of the NSW Greens, is in a battle against Labor’s Jodie Harrison, mayor of Lake Macquarie City Council.

Billionaire coal mining tsar Clive Palmer is financially supporting two independents, Jennifer Stefanac (Newcastle), and Suellen Wrightson (Charlestown), but neither is likely to receive more than a few hundred votes.

In the post-Nathan Tinkler era, shrewd Hunter voters are showing little interest in Palmer’s barmy rhetoric and cynical brinksmanship.

If Labor can’t produce a convincing win in two of its safest Hunter seats, blame will not fall on the candidates but on “Robbo”. It will resurrect the argument that Labor could do better at the March election with a more voter-friendly leader. (As preferred premier, Mike Baird scored 43% in the latest Galaxy poll while Robertson trailed on 15%. Another 42% were undecided.)

At another level, a strong showing by the Greens will mean trouble for Labor in the inner-Sydney seats of Balmain, Newtown, Summer Hill and Sydney at the state election.

That’s why the ancient art of reading tea leaves will be back in fashion as strategists from all major parties earnestly study results from the two byelections, with eight candidates contesting Newcastle and nine in Charlestown.