Retiring Trade and Investment Minister Martin Hamilton-Smith has made a significant contribution to South Australia during his four years in cabinet, Premier Jay Weatherill says.
Mr Hamilton-Smith, who sits in parliament as an independent Liberal, will not seek re-election in his eastern suburbs seat of Waite at the March state election.
The former leader of the Liberal opposition caused controversy in 2014 when he sensationally quit the Liberals to join the Labor government ministry.
"He decided to quit the Liberal Party and join a Labor cabinet because he wanted to make a difference, and that's exactly what he's done," Mr Weatherill said on Sunday.
"In defence industries, he's been a vocal advocate for South Australia's interests during a period when our state has secured record investment in the defence sector.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
"He's also helped nurture one of our emerging industries in space."
Mr Hamilton-Smith said it was time for him to step back from political life and focus on his family.
"After long consideration over the Christmas-New Year break I have decided that 21 years of public service, has been fulfilling and that now is the time to move on.
"I've delivered for SA and my local community almost everything I set out to do,."
Mr Hamilton-Smith entered state parliament in 1997 and served as a Liberal government minister before Labor won office in 2002.
He became opposition leader in 2007 but after losing support within the Liberal ranks called a leadership vote in 2009.
After winning the ballot by just one vote, he surprisingly instigated a second vote in a bid to seek a stronger mandate.
He lost the second ballot to Isobel Redmond.
After his defection in 2014, Mr Hamilton-Smith was dubbed a traitor by his former colleagues while recent opinion polls suggested he faced almost certain defeat in Waite at the March state election.
He will officially stand down from cabinet at its next meeting on January 18 and will not be replaced ahead of the March poll, with his portfolios to be allocated to the premier.
