Former SA Liberal MP willing to back Labor

Former Liberal Martin Hamilton-Smith will back either major party at the 2018 state election.

Former South Australian Liberal leader-turned-independent Martin Hamilton-Smith says he will consider doing a deal with whichever party wins the most seats at next year's state election.

Mr Hamilton-Smith has not ruled out supporting his old party or Labor in order to bring about stable government.

"If either of the major parties was within one vote of a majority, I think all of the independents would be under a lot of pressure to give South Australians stable government," Mr Hamilton-Smith told ABC radio on Monday.

Mr Hamilton-Smith who represents the seat of Waite in Adelaide's inner south-east shocked politics when he resigned from the liberal party after the 2014 election to join the Labor cabinet as minister for trade and Defence industries.

The former SAS soldier was elected to parliament for the Liberals in 1997 and was party leader from 2007 to 2009.

He is no certainty to retain his seat at the election in March with a strong challenge expected from Liberal candidate Sam Duluk.

Mr Duluk is currently the member for Davenport but will stand in Waite after a redraw of the state's electoral boundaries.

The seat could also be targeted by the party of popular senator Nick Xenophon, who will run candidates in a number of state electorates next year.