Alberta Premier Ralph Klein has submitted his resignation, officially triggering the race to replace him in the post he has held for the past 13 years.

Speaking to reporters at a fundraising event for Calgary's historic Heritage Park, Klein, 63, said he submitted his letter of resignation to party executives a week ago. However, he said he kept it quiet until after a task force report on crystal meth -- headed by his wife Colleen -- was submitted.

"I gave Colleen a commitment that I would withhold the announcement," Klein said.

Klein's resignation kicks off the race for the nine candidates vying to replace him as premier. Party executives are expected to announce the start dates later in the day.

"Doug Graham, the party president, will be laying the ground rules for all of the candidates -- how they will conduct themselves, and where the forums will take place and so on. As well, he will submit my letter of resignation and a statement," Klein said.

Klein said he will watch the race to replace him "with interest'' but won't be an active participant.

"I'll pay attention to what they have to say, but I'll keep out of the race,'' he said. "I'm not supporting overtly any candidate. I haven't made up my mind who I'll be voting for, but I will be voting.''

Nine contenders have thrown their hats in the ring to replace Klein, who plans to step down by the end of the year following the selection of a new leader.

The list includes former cabinet ministers Lyle Oberg, Mark Norris, Jim Dinning, Victor Doerksen, Dave Hancock and Ed Stelmach. Two backbenchers, Ted Morton and Alana DeLong, are also in the race as is disabled rights advocate Gary McPherson.

In a rare interview, Klein's wife Colleen spoke with CP this week, sharing some of her thoughts on the Klein's retirement.

"I've been very blessed, personally. It's been a wonderful adventure," she said. "But it's time to go on another adventure."

In keeping with Wednesday's low-key plans, she said the couple doesn't want to see any grandiose efforts to mark his resignation.

"Don't go naming things after us,'' she said. "My God in heaven, we've been down that road already."

She emphasized, however, that the past 13 years have been a joint effort, and used the word "we" when discussing their legacy.

"I just want to have it remembered we made a difference,'' she said.

"The legacy will be in our heart, because we know what we tried to do. Whatever the perception might be out there, we know that we tried to do the best we could.''

Klein plans to take several months off before tackling new duties as a guest lecturer at the Woodrow Wilson International Centre for Scholars in Washington, D.C., and as a member of two conservative think-tanks -- the Fraser Institute and Preston Manning's Manning Centre for Building Democracy.

His last few months in office have marked a rocky end to a successful career.

In March, Klein's retirement was bumped forward by several months after he received only lukewarm support in a vote by party delegates.

And a backlash has ensued in recent weeks after Klein's candid admission that his party hasn't prepared a plan to deal with the province's rapid growth due to its strong energy-based economy.

Former Alberta premier Peter Lougheed accused the administration of garnering a low return on oil which has been selling at record prices, and claimed the government is responsible for a lack of housing and services in the province.

Klein was roasted by about 250 well-wishers at a Tuesday night dinner to raise money for the Canadian Progress Club.

With files from The Canadian Press