Tough battle in SA as Xenophon rises

Labor admits it is facing a tough contest in South Australia, as support grows for independent senator Nick Xenophon and his running mates.

An analysis of Newspoll shows the Nick Xenophon Team has a primary vote of 22 per cent, just five points below Labor.

"There's no point downplaying it, this is a very contested election in South Australia and so it should be," the ALP member for Wakefield Nick Champion told ABC radio on Tuesday.

Cabinet minister Christopher Pyne, who holds the Adelaide seat of Sturt, says the choice between the major parties and the Nick Xenophon Team comes down to "stability versus instability".

"Nick Xenophon and his candidates, almost all of whom are utterly unknown, refuse to say who they would back if they had the balance of power in the House of Representatives," he told ABC radio.

"So a vote for NXT in the House of Representatives is a vote for instability, chaos and dysfunction and we've seen that movie before."