Gary Mar, a former health minister from the Ralph Klein era, and Alison Redford, Stelmach's former justice minister, were both hovering at around 40 per cent of the vote by party members, with half the 85 polls reporting.
Former deputy premier Doug Horner was third at about 20 per cent.
Voters named their first and second choices on their ballots.
If any of the candidates failed to get a majority, the third-place finisher's second-place votes would be redistributed accordingly.
The eight-month leadership campaign was criticized as being too long and devoid of galvanizing policy debate.
Mar was the front-runner from the moment in mid-March when he left his job as Alberta’s envoy in Washington to run.
He was challenged not only by Horner and Redford, but also backbencher Doug Griffiths, former finance minister Ted Morton and Rick Orman, an oil executive who was energy minister two decades ago under former premier Don Getty.
Mar finished on top in the first round of balloting with 24,195 votes, good for 41 per cent. But that was well short of the majority needed for a victory, forcing Saturday’s second round of voting.
Redford was second with 11,127 votes (19 per cent) while Horner was third with 8,635 (14.5 per cent). As per party rules Orman, Griffiths and Morton dropped off the ballot. In the days that followed, they threw their support to Mar and urged their supporters to do the same.
Mar, in fact, enjoyed the support of more than half the Tory caucus, along with the endorsement of former premier Klein.
The candidates squared off in several debates across the province. They were derided as tame affairs, given the debate format did not allow for cross-talk.
They all agreed on motherhood issues, including working within a balanced budget and listening more to voters and grassroots party members.
Health care, however, proved to be a dividing issue.
Mar made the biggest headlines of the campaign when he said he would look at all options, including expanded privately delivered care, to fix a health system struggling with long wait lines and substandard care.
Horner and Redford tried to leverage it as a wedge issue, with both promising to fix the system from within.
Horner said he would give nurses and other specialists more powers within their scope of training, such as signing off on prescription renewals, to free up doctors for more important tasks.
Redford said she would push for improvements to family care centres and primary care teams of specialists.
The winner faces the substantial task of revitalizing a party that has seen its right flank hived off to a certain degree by the rival Wildrose party.
Under Stelmach, three members of the Tory caucus crossed the floor to join leader Danielle Smith’s party, and if recent polls prove accurate, the Wildrose will take a bite out of the Tories in the next election.
The Tories do not have to go to the polls again until March 2013, but a general election is expected either this fall or next spring.