Municipal affairs activist and former Winnipeg mayoral candidate David Sanders has died of cancer.

A lawyer by training and a property tax consultant, Sanders had been a fixture at city hall since the Sam Katz administration. He made frequent presentations to council committees and council as a whole, most often regarding financial and process issues.

He also ran for mayor in 2014, finishing fifth in a field of seven candidates, and was appointed the chair of the Manitoba Taxicab Board after the election.

Sanders died on Sunday around 6 p.m., just over a month after he was diagnosed with colorectal cancer, his son Jim said. He was 69.

The cancer was advanced and Jim said "he didn't suffer long" before passing away.

"I always said my dad had the biggest, most pure heart I knew. He infused in me and his children a kind of sense of service to others and activism," Jim said.

Jim said his dad was committed to fairness, equality and social justice.

"On some level, he represents overall what so many of us are hoping for: that peace, that fair society, and a fair Winnipeg. He had so much faith in the potential of Winnipeg and Manitoba. He always kept up hope."

Premier Brian Pallister described Sanders as a lifelong advocate.

"David cared deeply about making the city of Winnipeg and the province of Manitoba better for their citizens," he said in a statement. "David was dedicated to his community, family and local government."

Winnipeg Mayor Brian Bowman described Sanders as a man who cared deeply about the city.

"Throughout the 2014 election, David was very passionate about Winnipeg, and cared deeply about making Winnipeg better," Bowman said in a statement.

"David was dedicated to our community, and he demonstrated his commitment through active participation and leadership in university, schools, sports, community and charitable organizations."

South Winnipeg-St. Norbert Coun. Janice Lukes, who was an activist before she became an elected official, said she valued Sanders' contributions.

"I was an advocate for many years. I would watch him come down to city hall. There's always value in advocacy work that people do, and there's lots of truths in what people bring forward as an advocate," she said at city hall.

"You need all kind of people in this role, because it brings all kinds of perspectives forward. He brought forward a lot of very interesting perspectives and thoughts."

David Sanders, left, listens as Gord Steeves speaks during the CBC mayoral debate in Winnipeg on Oct. 15, 2014. (Michael Fazio/CBC)

With condolences being shared online by officials and citizens, Jim Sanders said it's clear his father's reach was considerable. But David Sanders' greatest legacy will be as a father, his son said.

"My dad was an amazing dad, he was amazing," Jim said. "I'm remembering a lot of that right now. He was always there for me.… It will be a huge loss for me to not have him by my side."

In a 2014 interview with the CBC, Sanders spoke about his family's connection to Winnie the Pooh.

David Sanders had far-reaching roots in Manitoba. (Courtesy David Sanders) "He [Winnie the Pooh] lived in the Hundred Acre Wood in a hollow tree under the name of Mr. Sanders, and that was my father," said Sanders. "My father actually fought in the First World War.… He was wounded in France, and he was in hospital in southern England, and his bed mate was [Ernest Shepard], who was the illustrator for Winnie the Pooh."

In a post on Facebook, Jim referenced the fictional bear's relationship with his family.

"Mr. Sanders is now with Pooh Bear & his friends in the 100 Acre Wood," he wrote.

He also said his father was the conscience of the city and worked tirelessly to help others.

"I will miss him dearly. I know his spirit now overlooks our city, this province, and will infuse the hearts of all those dreaming and working for a truly beautiful city where we are all together as one."