Former Conservative cabinet ministers Jason Kenney and Peter MacKay are urging the new leader to strike an optimistic, inclusive tone and to continue campaigning across the country as soon as he or she is named on Saturday.
The two were once considered natural successors to former prime minister Stephen Harper, but chose not to run in the race to lead the Conservatives into the 2019 election.
Mr. Kenney returned instead to Alberta in a bid to unite the provincial Tories and Mr. MacKay, who has two young children, joined an international law firm in Toronto – although he is still leaving the door open to returning to Ottawa one day.
"Politics is always in your blood," Mr. MacKay said in an interview. "I'm not ruling it out. Why would I?"
Their decisions to stay out of federal politics for now significantly boosted the prospects of lesser-known candidates, with Quebec MP Maxime Bernier considered the front-runner among the 13 contenders.
But with a preferential voting system and a record number of ballots cast in a leadership race, the contest has been difficult to predict, and some in the party think former speaker Andrew Scheer or Ontario MP Erin O'Toole could surprise with enough second- or third-choice support.
Whoever wins, Mr. MacKay said, needs to be both approachable and visible as soon as the race is over.
"It's going to take a lot of hard work on the ground and that means, unfortunately for whoever the leader is, a continued offensive to get out into the country as much as possible," Mr. MacKay told The Globe.
"I don't think that the new leader has any choice but to embark on even further campaigning."
He said the new leader should follow the example set by interim Leader Rona Ambrose, who was praised for softening the tone of the party under her 18-month watch.
"Whoever succeeds Rona has to continue in that vein, of being seen as the inclusive party, the party that is tolerant, the party that is a viable alternative to the Liberal government on policy matters," he said, citing lower taxes, greater support for the military and increased accountability as examples.
Mr. Kenney now leads Alberta's Progressive Conservatives and will run for leader of the United Conservative Party if PC and Wildrose members give it the green light. He said the federal party has a "huge opportunity" to run on economic issues in the next election, as long as the party regains "a sense of optimism and persuasiveness."
"I've always believed that the Harper government was defeated not so much on policy grounds, as because of its tone and the approach to communicating at the end of the government," he said.
"It looked like we were going out of our way to make enemies and not friends."
Mr. MacKay, who led the Progressive Conservatives in 2003 before it merged with the Canadian Alliance to form the modern Conservative Party, said he thinks the party is coming out of the race united.
"These leadership contests can be very bruising affairs, as I can attest. And they can be very divisive. They can get personal. I haven't seen any of that, quite frankly," he said.
Mr. MacKay will be attending the weekend leadership event, but Mr. Harper, Mr. Kenney and former Reform Party leader Preston Manning won't be there. Neither Mr. MacKay nor Mr. Kenney would say whom they are supporting in the race.
"All of the people who appear to be front-runners, I think they're great people … I'd be happy with any of them," Mr. Kenney said.
When asked whether the front-runners included Mr. Bernier, Mr. O'Toole, Mr. Scheer and Kellie Leitch, who proposes to screen immigrants for Canadian values, Mr. Kenney, the former immigration minister who has criticized her policies, replied, "I wouldn't define Kellie as being in that vein. But I've made my views known about her campaign."
"I think there's a lot of good people to choose from who have a very positive, hopeful message," he added.
But some Conservatives think it will take more than a hopeful message to win the next election.
Rachel Curran, Mr. Harper's former policy director who's currently a senior associate at his international consulting firm, said the new leader needs to define his or her own vision for the party, which includes detailed policy platforms.
"I don't think you are going to win an election by offering a version of the Stephen Harper agenda," Ms. Curran said.
While Mr. Bernier has proposed radical ideas about stopping supply management, overhauling the tax system and ending corporate subsidies, Ms. Curran said they are almost impossible to achieve.
"The things he has proposed – there is no possible way that there's room in the fiscal framework to do them," she said.