19/10/2017 7:08 AM AEDT | Updated 19/10/2017 7:08 AM AEDT

Xenophon The Preferred Premier For South Australia: Poll

Xenophon's SA Best party leads Labor by 4 percent.

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Nick Xenophon will depart Federal Parliament to run for a state seat in South Australia.

Outgoing federal senator Nick Xenophon has been named as the preferred premier for South Australia as he prepares to contest the March state election.

A privately commissioned Galaxy poll puts Senator Xenophon's party in a tight second position in the primary vote, with the Liberals on 31 per cent, SA Best on 30 per cent and the incumbent Labor Party on 26 per cent.

The statewide poll of 806 voters last week reveals Senator Xenophon, who will stand in the state seat of Hartley, as the preferred premier with 41 per cent support, compared to Premier Jay Weatherill and Opposition Leader Steven Marshall both on 21 per cent support, The Australian reports.

SA Best will field up to 20 candidates in lower house seats Senator Xenophon believes they can snatch from the two major parties, while five candidates will run for the upper house.

Senator Xenophon is one of seven federal MPs whose citizenship status is before the High Court - his mother was born in Greece and his Cyprus-born father held a British passport.

It's unclear when the High Court will hand down its ruling.

In the Senate on Wednesday night, he said he did not know when he would be making his last speech, but hoped "this won't be it, because I have a lot to say about many issues affecting my home state of South Australia".