EDMONTON -- The race officially began for Alberta's governing Progressive Conservatives Thursday with two candidates picking up their nomination forms.

Former federal cabinet minister Jim Prentice used social media to send a picture of himself picking up the paperwork. His caption was "Off to collect signatures."

Calgary legislature member Ric McIver directed supporters to the party website and urged them to take out memberships.

Both candidates had to deliver a $20,000 non-refundable deposit.

They must pay another $30,000 when nominations close at the end of the month and deliver 500 signatures from party members endorsing their nomination.

There must be 100 names each from five regions: Edmonton, Calgary, north, south and central.

All confirmed candidates are to be introduced at a forum in Edmonton on June 2. Jobs Minister Thomas Lukaszuk has said he may run as well, but has yet to confirm.

Prentice, who held portfolios in Prime Minister Stephen Harper's cabinet, is considered the front-runner. He has yet to speak about why he wants the top job and what his vision is for Alberta. But he already has the public support of 17 Tory members of the legislature.

McIver, who stepped down as infrastructure minister to enter the race, is promising to run a populist campaign intended to eradicate spending scandals that helped bring down former premier Alison Redford.

There are to be a series of roundtable discussions between the contenders starting May 24 in Edmonton and May 31 in Calgary.

Prentice's team confirmed Thursday that Shirley McClellan, a Tory cabinet minister from the Ralph Klein era, will be one of four campaign leaders. The others are current Human Services Minister Manmeet Bhullar, Jay Hill and Patricia Misutka.

Premier Dave Hancock said it's not unusual for ministers to get directly involved in leadership campaigns while sitting in cabinet. He said he doesn't expect it will affect Bhullar's cabinet responsibilities.

"It's very important that the work that needs to be done get done, and (Bhullar) knows and understands that," said Hancock. "It's also very important that we keep the two separate, that the work of government does not overlap with the leadership process."

Party members vote Sept. 6. If a third candidate joins the race, the winning candidate will have to get more than 50 per cent of the votes on the first ballot. If that doesn't happen, the top two move on to a final runoff vote Sept. 20.

The race has been noteworthy to date for what hasn't happened.

Cabinet ministers Doug Horner, Jonathan Denis and Diana McQueen, considered contenders, decided not to run and instead back Prentice.

Prentice's camp has denied comments from Opposition Wildrose Leader Danielle Smith that someone in his camp reached out to suggest a merger should Prentice win.