West Australian Treasurer Ben Wyatt will quit state politics next year, citing family health reasons as a factor, ending a 15-year career in parliament.
Mr Wyatt, who is also responsible for the Aboriginal affairs, lands and finance portfolios, will continue in his current roles until the March 2021 election.
"My family has experienced a personal health issue, which prompted this consideration and the kind of future I want to have with my family," he said on Tuesday.
"While I do not intend to go into the finer details of these personal experiences, today I am announcing that in the interests of my family I have decided not to stand as a candidate at the 2021 election."
Mr Wyatt said while his decision had not been easy, he wanted to consider "other options" with his family.
"My children are of an age that leaves me with a short time to relish new experiences with them, while they still want to hang out with me and before they reach senior levels of high school," he said.
Mr Wyatt entered parliament in 2006 following the Victoria Park by-election, triggered by the resignation of former Premier Geoff Gallop.
In 2017, the 45-year-old former lawyer, who is related to federal minister Ken Wyatt, became the first indigenous treasurer at a state or federal level in Australia.
Mr Wyatt thanked Premier Mark McGowan for his "unwavering support" and friendship, and said his time in politics had been an incredible experience.
"I doubt I will ever have a job as diverse, challenging and satisfying as the role I have had as treasurer of the state," he said.
"Last year, I delivered my third budget ... I had achieved the most important outcome that had been set for me at the 2017 election. That is, to return the economy to growth and to restore the finances to health.
"Western Australia is now in surplus and we are the only state government in Australia that is reducing debt."
Mr Wyatt had sought to challenge for the Labor leadership in 2011, but withdrew when he realised he did not have the numbers to defeat then opposition leader Eric Ripper.
The following year, Mr McGowan was elected the leader unopposed.
Mr McGowan described Mr Wyatt as a close friend and said he had considered him to be a future premier of WA.
"I respect and understand his decision to bring his political career to an end next year and focus on his young family," Mr McGowan said.
"Political life has many challenges, but the hardest challenge is finding the right balance between work and family life. I know just how hard it is.
"Ben has done an exceptional job as the treasurer."
Political analyst Harry Phillips told AAP it was a sad day in politics, but it was difficult to measure how Mr Wyatt's departure might affect the forthcoming election.
"I think it will be a very serious blow to the Labor Party. I think he's highly regarded as a competent treasurer," he said.
"I would judge him as an outstanding treasurer and an outstanding parliamentarian. There are very few critics of his performance."
Mr Wyatt will hand down his final budget in May.
Australian Associated Press