Social Services Minister June Draude says she will not run again in the next provincial election expected in April 2016.
"After the last election, I had a discussion with my family. I knew that the last election was the last time I was going to run," Draude said Wednesday at the legislature in Regina.
"It's just a time to do something different in my life."
She has five children and eight grandchildren.
Draude was first elected in the constituency of Kelvington-Wadena as a Liberal in 1995, but two years later she joined with three other Liberals and four Progressive Conservatives to form the Saskatchewan Party.
She has also been minister responsible for Crown Investments Corporation and First Nations and Métis Affairs minister since the party took power in 2007.
Draude says a recent dispute over her ministerial travel expenses had nothing to do with her decision to retire.
The minister was under fire in the legislature earlier this month for using a car service in London that cost $3,600 over four days and for $200 spent on lunch with a friend. Those expenses were filed by the cabinet secretary and the clerk of executive council, who was on the trip with Draude last June.
Draude said she wasn't aware of the costs. The cabinet secretary has since repaid the expenses.
"I'm saddened by the fact that that was something that people will think about, but really what I'm happy about is that I had a chance to be part of not only starting a party, but building it and becoming government," she said.
Premier Brad Wall says Draude was a driving force in building the party. He says she has been its "heart" and served as an advocate for the most vulnerable in the province.
"It's another big loss," said Wall.
"For as long as I've been elected and as long as I've known June, she has reminded us — this free-enterprise oriented party that focuses on a lot on economic growth — that growth for its own sake is really not going to get us anywhere."
Earlier this week, deputy premier and Finance Minister Ken Krawetz — another founding member of the Saskatchewan Party — said he won't run again.
That means Wall will have to make some big decisions in a cabinet shuffle later this spring.
"I sort of reserve the right to select a cabinet as best I can. It's a difficult job, but I'll do the best job that I can and we have a good group to look at, to draw from," said Wall.
"I won't rule out completely those who have said they're not running again in this particular shuffle. I'm not going to do that, so everyone's a candidate. But I do think it's probably a medium-size (shuffle), if you're looking for a characterization from me, in terms of the scale or depth of it."