Jim Prentice was seen as a saviour to Alberta's Progressive Conservatives – a former federal minister and bank executive who could reverse the party's post-Alison Redford freefall.

He won the support of the vast majority of PC MLAs, including one cabinet minister who ended his own leadership campaign to back Mr. Prentice. The race to be premier was shaping up as a coronation. However, months later and with a vote three weeks away, Mr. Prentice's victory is far from secure.

This week, Mr. Prentice admitted his campaign handed out party memberships for free, which is not against the rules but is generally frowned upon. A membership is required to vote in the race. Mr. Prentice's spokesman had disavowed knowledge of the practice even after a secret audio recording from a rival campaign apparently showed three different Prentice volunteers telling a woman they'd waive the $10 fee, before introducing Mr. Prentice himself.

Story continues below advertisement

Mr. Prentice was left under fire from his two opponents, Ric McIver and Thomas Lukaszuk, former provincial ministers who have no other MLAs backing their bids. "What I'm seeing is he'll do whatever it takes to win, and that's a pretty hollow victory," Mr. Lukaszuk said. Handing out free memberships "definitely is buying a vote" as the Prentice campaign still has to pay the party for it, he added.

Mr. McIver said handing them out for free "brings down the relative value of our party instead of building it up, and I'm disappointed with that," but he avoided directly attacking Mr. Prentice on the issue.

However, the trio face another unavoidable issue in the race: the political ghost of Ms. Redford. Revelations about the former premier's travel spending and habits have continued to dog the PC party throughout the summer, and party sources say all campaigns are struggling to sell memberships.

"I think the Prentice team is absolutely panicking. Giving away free memberships is one thing. Admitting to giving away free memberships is unheard of. No one's buying them," said one source familiar with the race but unaffiliated with any campaign. "And if no one's buying them, how many people are going to vote?"

The source estimated turnout could be as low as 25,000, compared to the 59,537 votes cast in the first ballot of the 2011 leadership race won by Ms. Redford. A veteran politician backing Mr. Prentice nonetheless estimated he will win on the first ballot. Another source said the "safe money" is still on Mr. Prentice, but "this one's so hard to call."

"The only hope that Thomas or Ric have, of course, is a low turnout," the source said.

Precise membership figures are impossible to nail down as each campaign database remains private – unlike the 2011 race, no master list will be created until after a new leader is chosen. Mr. Lukaszuk played down expectations.

Story continues below advertisement

"You're looking at a leadership that is only three months, with only three candidates in the middle of summer," he said. "And let's be honest, at a time when we're dealing with some unpleasantries, to say the least, from the last premier."

Mr. McIver was coy about how sales were going. "We've got a steady stream of them coming in. It's not necessarily easy but I'm not sure it should be easy to become premier," he said in an interview Thursday. He acknowledged the PC brand "has been diminished in some ways" by Ms. Redford. "You celebrate the good and you correct the bad. That's what I've been talking about. That's what I have plans to do. That seems to be resonating with Albertans," he said.

A spokesman said Mr. Prentice was unavailable for an interview. The campaign declined to issue a statement, but the Calgary Herald reported Thursday Mr. Prentice said the campaign would continue to give out free memberships to ensure "as many people taking part in the democratic process as possible."

Calgary pollster Janet Brown said "the recent moves by Prentice appear to be somewhat desperate," but said there's little evidence to say what will happen, and no reliable polling given the secret nature of the party membership lists.

"All indications look like Prentice should get it on the first ballot, but that's just tea leaves," she said.

The first ballot is set for Sept. 6. If no candidate gets a majority, the top two go to a second ballot on Sept. 20.