SA-BEST leader Nick Xenophon says he still believes the South Australian election will be a three-way contest between his group, the sitting Labor government and the Liberal opposition.
But the former senator admits even winning his own seat will be a challenge.
After peaking in December, recent opinion polls have support for Mr Xenophon's group behind that of the Liberals and Labor.
Even in his own seat of Hartley, he's seen as the underdog behind sitting Liberal Vincent Tarzia.
But he hasn't given up on the goal of SA-BEST seizing the balance of power.
"In a number of seats, this will be a genuine three-cornered contest and I think that's a good thing for democracy," Mr Xenophon said.
"But I'm always worried and it's going to be tough. I'm trying to defy political gravity."
Labor and the Liberals have targeted Mr Xenophon and SA-BEST during the campaign while the Australian Hotels Association has also run a major advertising blitz over his policy to cut the number of poker machines in SA by half, warning it will cost jobs.
Mr Xenophon says the campaign against him is based on lies and latest research shows that poker machines actually cost jobs in the community
But Foreign Minister Julie Bishop said a vote for SA-BEST would be wasted and criticised Mr Xenophon's record.
"He's never had to deliver on anything," she told reporters on Sunday while campaigning in the Adelaide Hills.
"So a vote for him would be a wasted vote."