Former South Australian premier Jay Weatherill vowed to serve a full term but says he doesn't believe he is letting anyone down with his decision to go.
Former South Australian premier Jay Weatherill is to quit state parliament, bringing an end to his 16-year political career.
Mr Weatherill says it's been a privilege to serve as an MP, minister and premier and he remains proud of the previous Labor government's achievements.
After the state election defeat in March, the former leader vowed to serve a full four-year term but said on Thursday he didn't believe he was letting anyone down with his decision to go.
"It's time for me, having run my race, to hand the baton on," he told reporters, flanked by his wife and two young daughters.
Mr Weatherill also cited the difficulties posed for political parties when former leaders hang around.
"Obviously I've got points of view but if I share them, even with the caucus, it creates attention," he said.
"It's difficult to have such strong views and not being able to share them."
Mr Weatherill ruled out a tilt at federal politics and said he intends to spend more time with his family.
He offered them a special tribute in his resignation speech.
"I don't know how, frankly, you can be sustained in a leadership role in politics without the love and affection of a family," he said.
"It's tough, it's really tough. You need family or friends or some other support system to allow you to get through things."
Mr Weatherill entered the parliament in 2002 and served as SA's 45th premier from October 2011 until Labor's election loss.
His departure is likely to clear the way for a by-election early in the new year with Labor's candidate for the safe seat widely tipped to be Unions SA secretary Joe Szakacs.
Current Labor leader Peter Malinauskas thanked his predecessor for his service.
"When Jay's back was up against the wall and it was time to stand up and fight for our state, he did exactly that," Mr Malinauskas said.
"Jay's steely resolve and furious commitment to the people that he cares about came to the fore in a way that saw a quality public policy effort combined with considered politics."
Among others who sent their well-wishes to Mr Weatherill was former prime minister Julia Gillard, who described him as "a great leader and thinker".