Former deputy prime minister John Manley will not run in the upcoming Liberal leadership race, he said in a statement Tuesday.
Last week, Manley openly considered tossing his hat into the ring but expressed uncertainty about entering what would be his second leadership contest.
In a letter sent to colleagues and supporters, Manley said he "consulted broadly" with family and friends and was "greatly moved" by the offers of support and financial help.
But in the end, he says he was unable to envision re-entering "political wars" as an "active, partisan combatant."
"I truly found that in my mind and heart that I have moved on from the world of elected office," he wrote. "I also found that I lacked the burning ambition necessary to mount and sustain such a campaign."
He goes on to express his pride in having served in government and hopes there will be "opportunities for me to serve in the future," but it is unlikely to involve an elected post.
Manley served as minister of a number of departments during his 16 years as a member of Parliament, including Finance, Foreign Affairs and Industry, but has worked off Parliament Hill for the past few years.
The 58-year-old currently practises law in Toronto and Ottawa and sits on several corporate boards. He ran in the 2003 leadership campaign but withdrew months into the race amid growing support for front-runner Paul Martin, who went on to become leader and prime minister.
Liberal Leader Stéphane Dion announced last month that he would step down as leader once a successor is chosen.
His decision came a week after the Oct. 14 federal election, which saw the party's worst results in terms of popular vote in more than 100 years and reduced them from 95 to 77 seats in the House of Commons.
So far, only two Liberals — former Ontario premier Bob Rae and New Brunswick MP Dominic LeBlanc — have announced their entrance into the race.
Former New Brunswick premier Frank McKenna, who was considered a star candidate, has said he won't seek the leadership.
Those rumoured to have their eye on fighting for the Liberal helm include Montreal MP Denis Coderre, Toronto-area MP Ruby Dhalla and former leadership contenders Martha Hall Findlay and Gerard Kennedy
Toronto MP Michael Ignatieff is widely expected to run again after waging a close battle at the last leadership convention.
But CBC's Susan Bonner notes that there is mounting speculation that the field of potential candidates might be narrowing.
Bonner said the Liberal party executive plans to meet this weekend to set the rules for leadership race as well as the date for the convention and how much to charge for the entrance fee.