EDMONTON — The race to replace Alberta Premier Ralph Klein heated up Tuesday as one contestant put himself in the starting blocks by quitting cabinet.

Ed Stelmach, Klein's intergovernmental relations minister, resigned the post in keeping with the premier's recent order that ministers wishing to run for the Progressive Conservative leadership should resign by June 1 to avoid a conflict of interest.

Stelmach became the first minister to resign, but he insisted he was not firing the starting gun.

"Officially, there is no race. The campaign will kick off when the premier announces his resignation," Stelmach told reporters after announcing his decision to the government caucus.

"It may even say that 'Look, there's no doubt about it. We're here, we mean business and we're in the race.' "

Stelmach said his early departure from cabinet will give him more time for his leadership activities and allow for a smooth transition within his department.

"Sometimes where you're reaching for a goal there are sacrifices," he said. "As was said before, it'll level the playing field. I feel good."

Two other cabinet ministers are among the possible candidates for the Tory leadership when Klein officially steps down, expected in two years.

Transportation Minister Lyle Oberg has already said he'll resign by June. There have been rumblings that Oberg might also leave cabinet earlier, but the minister was in Ottawa for meetings Tuesday and could not be reached for comment.

Advanced Education Minister David Hancock has said he wants time to weigh his options before deciding whether he'll leave cabinet.

The other leadership candidates include former treasurer Jim Dinning, defeated cabinet minister Mark Norris, and rookie government member Ted Morton.

Klein is facing a mandatory leadership review by Conservative delegates who attend the party's annual general meeting at the end of this month.

The premier confirmed recently that although he plans to resign at the end of October of next year, he'll remain on the job until about March 2008 while a new leader is chosen.

But Klein has also said he'll leave early unless he gets a strong show of support from Tory delegates when they vote on March 31.