Rudd said while he was "not a big punter," his government still had a chance to win a third three-year term.
He pointed out that a favorite had only won the Melbourne Cup, Australia's premier thoroughbred horse race, 35 times in 151 years. (Far from a two-horse race, the Cup had a field of 24 last year when Green Moon won).
Rudd acknowledges he is the underdog but also pointed out that Liberal Leader John Hewson was favored at elections in 1993, but Labor stayed in power.
"He was the favorite and regarded as a shoo-in," Rudd told reporters of Hewson. Rudd accused Abbott of avoiding scrutiny of his coalition's policies because he was convinced victory was inevitable.
"Because he believes he has the election in the bag, he believes he can get away with not being truthful with the Australian people," Rudd said.
But Abbott said his experience as Hewson's press secretary in the 1993 election campaign made him wary of his own prospects.
"As for the bookies, I'd say more fool them," said Abbott, in a variation of a Shakespearean line.
Abbott added: "1993 is proof that there is no such thing as an unloseable election, and I think this election is very, very tight," he added.
Labor has been lagging behind Abbott's coalition in opinion polls for more than two years.
There was a resurgence in Labor popularity immediately after Rudd replaced Prime Minister Julia Gillard in a leadership ballot of government lawmakers in June. But Labor support appears to have plateaued below the opposition in the final weeks of the election campaign.
Lane said Sportsbet would not seek a refund from gamblers in the event of an upset Labor win.
"Nine days is a long time in an election campaign, so anything can happen," Lane said. "At this stage, we're pretty comfortable that we've backed the right horse, so to speak."
The biggest bet to date was AU$750,000 for a coalition victory made on Monday when the price was AU$1.07. The punter made AU$52,500.
