Nick Xenophon's SA Best party is more popular with South Australian voters than either the Labor or Liberal parties, and almost half of the state's voters want the former senator to be their next premier, according to Newspoll.

Newspoll results: 32 per cent of voters favour SA Best

32 per cent of voters favour SA Best 46 per cent prefer Nick Xenophon as premier

46 per cent prefer Nick Xenophon as premier Support for Greens falls 9 to 6 per cent

The latest poll, published in the Australian newspaper, shows 32 per cent of SA voters intend to direct their first preference votes to SA Best during the March election, compared to the Liberal Party on 29 per cent and Labor on 27 per cent.

The stunning result for the SA Best party, which did not exist at the time of previous polls, means Newspoll has been unable to calculate a meaningful two-party-preferred vote between the major parties.

It shows Nick Xenophon, who intends to run for the Liberal-held seat of Hartley, is more popular than Premier Jay Weatherill and Opposition Leader Steven Marshall by a factor of more than two to one.

Some 46 per cent of voters prefer the former senator as premier, compared to 22 per cent who prefer Mr Weatherill and 19 per cent who prefer Mr Marshall.

But it is not yet clear whether Mr Xenophon will be in the premiership race.

The former senator has declared his intention to hold the balance of power in SA Parliament, but has ruled out accepting ministries or forming coalitions with a ruling Liberal or Labor government.

He has so far announced just six candidates in addition to himself, all running in Liberal held seats.

One candidate, Rhys Adams, was sacked the day after the announcement after the ABC revealed his Facebook history included an image that appeared to make light of domestic violence.

Mr Xenophon has suggested another raft of candidate announcements would be made this week.

He said he intended to contest about 20 seats in the 47-seat House of Assembly.

"We are running in seats where we think we have a real chance of winning, of causing an upset," Mr Xenophon said.

"And the fact that SA Best, which is basically a start-up, a fledgling party with a fraction of the resources of the major parties, is doing well in the polls indicates that people do want change."

Newspoll an early vindication for Xenophon

Mr Xenophon has suggested another raft of candidate announcements would be made this week. ( ABC News: Leah MacLennan )

The Newspoll result is an early vindication of Mr Xenophon's October decision to quit federal politics and pursue a state seat at the March 17 election.

The poll result will also give the major parties pause for thought as they strategise whether to preference each other in a bid to block the new rival, or SA Best in an effort to win the third party's support for a minority government in the event that neither major party can govern alone.

Compared to the last SA Newspoll conducted in 2015, SA Best has stripped 9 percentage points off the primary votes of each of the major parties.

Support for the Greens has fallen from 9 to 6 per cent.

Support for other minor parties, including Cory Bernardi and Family First's newly merged party entity, sits at 6 per cent.

The latest Newspoll data is based on interviews with 800 participants and has a sampling error of plus or minus 3.5 percentage points.