Jason Kenney may have left the national scene to immerse himself in Alberta politics, but he keeps an eye on the federal party he used to represent. And he sees a potential threat lurking in the Conservative leadership race — from within the party.

"I think ultimately the biggest threat is division," the former immigration minister under Stephen Harper told CBC News.

"We've gone through, in the not too distant past, a decade of division in the conservative movement in Canada and there are some people trying to call us back to that division to create two separate conservative parties. I think that's the biggest threat."

Division is a theme Kenney is intimately familiar with. He's just emerged from weeks of intense negotiations over a proposal to merge Alberta's two conservative political parties, the Progressive Conservatives, which he now leads, and the Wildrose.

It was not the path many expected for Kenney. When Harper announced he would step aside after his party lost the election in 2015, Kenney seemed like he would be a dominant force in the race to replace him.

Instead, Kenney opted for provincial politics, and now 13 candidates are vying to take on the title he spurned. The winner will be announced on May 27. Kenney believes division could come from the fallout of that race.

"After every leadership election there's a winner and there are losers — in this case there will be a lot of people who don't succeed, and some harsh things are said."

Potentially sore spots

Kenney didn't offer specific examples of fault lines in the party. While many of the leadership debates involved more agreement than discord, there have also been a few potentially sore spots in the federal race.

Kellie Leitch has attracted considerable criticism for her proposal to screen all visitors and immigrants to Canada with a test for what she describes as Canadian values.

Rival Maxime Bernier called her a "karaoke version of Donald Trump," while another leadership candidate, Michael Chong, said "wannabe demagogues" like Leitch have created the environment that led to the Quebec City mosque shooting in which six Muslim men were killed.

Federal Conservative leadership candidates Maxime Bernier, right, Kellie Leitch and Andrew Scheer are among those who have been the subject — or source — of attacks. (Nathan Denette/Canadian Press)

Candidate Lisa Raitt actually announced a campaign targeting what she called the "irresponsible populism" of Leitch and businessman Kevin O'Leary. She even launched the web site www.StopKevinOLeary.com.

O'Leary himself was a divisive figure at times, slagging "mediocre career politicians" in one speech. He's since dropped out of the race and backed Bernier.

During the last official debate in Toronto, Erin O'Toole took aim at Andrew Scheer for his time as as Speaker of the House of Commons, a non-partisan role. O'Toole accused Scheer of deciding to "leave the field of battle" and party colleagues in order to "hold receptions" at the Speaker's official residence.

Even debates over dairy have created division. Bernier has pledged to end Canada's system of supply management, much to the derision of Scheer and Steven Blaney, who have openly courted votes from farmers.

Next challenge: Beat Trudeau

Kenney said he has already sent in his mail-in ballot to select a new federal leader. But he won't offer up any endorsements or even hints about who he's supporting.

"No," he said with a laugh, when pressed. "Secret ballot."

He did say that whoever wins should be expected to not simply improve the Conservatives' seat count, but to beat Prime Minister Justin Trudeau in the next election, though he notes that history suggests most Canadian governments get a second mandate.

Many Canadians are growing a little bit weary of government by photo op. — Jason Kenney

"It's ambitious, but I'm sure whoever is going to be elected leader isn't shooting to lose the next election. There are going to be challenges, but my sense is many Canadians are growing a little bit weary of government by photo op," he said, taking a veiled shot at Trudeau's approach.

While he does believe there is an opening for the Conservatives, he said for that opportunity to be realized, the party will have to ensure it remains united.

"Here I am in Alberta working to overcome a decade of division in Alberta politics between conservatives. So this stuff happens."​

"United, we're stronger."