In a surprise announcement, Glen Murray has vowed not to run for election again. ((Canadian Press) )

Glen Murray, a veteran cabinet minister in successive Ontario Liberal governments, has promised that he's run in his last election.

"Today it sunk in the last election was my last," Murray announced on Twitter. "Promised that if I couldn't make a difference in eight or ten years I couldn't make a difference."

The 56-year-old won his seat in Toronto Centre handily in the June 12 election. He has been a notable presence in both Dalton McGuinty's government and Kathleen Wynne's, serving as a cabinet minister in both.

He was formerly the mayor of Winnipeg. He was the first openly gay politician elected in Canada. Murray, often seen wearing a bow tie, was elected three times in Toronto Centre.

Murray was named minister for the environment in the newly elected Kathleen Wynne government. He was previously the minister responsible for transportation.

There is rampant speculation that Murray was upset with his shift in responsibilities, and announced his intentions to end his career as an elected official in response to taking over the environment file.

His unexpected announcement aside, Murray will continue in his seat for the duration of the current Wynne mandate, expected to be four years at least.