Former Australian Medical Association President, Bill Glasson, managed a 5.5 percent swing against Kevin Rudd at the fderal election last September. But he acknowledges he remains the underdog.
A government hasn't won an opposition-held seat at a by-election in almost a century.
"It's an exciting challenge and I think it comes down to appealing to the people to say to them 'listen this is not about changing the government'," he said.
"On Sunday morning, Mr Shorten will still be the Opposition leader and Mr Abbott will still be the Prime Minister."