A former top strategist for Stephen Harper says Conservative leadership candidate Kevin O'Leary doesn't know the party's base, and its unity could be at risk if he wins the top job.

Jenni Byrne, the Conservative Party's 2011 and 2015 campaign manager, laid out a range of concerns about a possible O'Leary leadership.

"Although people remark that he is very Trump-like, he's actually completely the opposite," Byrne told Evan Solomon, host of CTV's Question Period.

Trump "knew his voter coalition, he knew the out-of-work steelworkers and autoworkers in Michigan and Pennsylvania and Ohio, and he spoke to them every single day... He knew who his base was," Byrne said.

In contrast, she said, O'Leary doesn't know the Conservative Party base, which risks breaking apart the coalition former prime minister Stephen Harper built.

"He has dismissed the war on terror, he's insulted the military, so he's coming in as someone completely the opposite," Byrne said.

"It will be a challenge for anyone coming in, in terms of keeping that coalition together. And I think that for the reasons we've said, I think Kevin O'Leary is the candidate that probably least understands that."

As the campaign manager, Byrne was widely credited with the Conservative Party's 2011 win, but shouldered the blame for its struggles in 2015. She remains friends with Conservative leadership candidate Erin O'Toole, although both have said she isn't involved with his campaign.

A spokesman for O'Leary noted Byrne's connection to O'Toole and said he's focused on winning the leadership so the party can defeat Prime Minister Justin Trudeau in 2019.

"Our campaign does not believe in fighting with other conservatives," Ari Laskin said in an email to CTVNews.ca.

O'Leary has been criticized for frequent trips to the U.S. during his brief leadership bid -- he joined the race in mid-January, months behind the other candidates -- and has fended off questions about whether he lives in Boston as opposed to Canada.

That's drawn comparisons to the Conservative Party's 2011 attack ads against then-Liberal Party leader Michael Ignatieff, who had returned to Canada from Boston to run for office.

"If I was a Liberal campaign manager, I would be salivating at the thought" of an O'Leary win, Byrne said, noting Ignatieff didn't live in his riding but at least made his home in the same area code.

Despite that, Byrne says she believes the O'Leary campaign's claim that they've sold more than 30,000 memberships -- a number that's difficult to verify -- and says O'Leary has a real chance of winning.

Those memberships, however, don't guarantee support for any particular candidate. Leadership contestants still have to convince members to cast their ballots. Plus, because the party uses a run-off system, voters' second and third choices will likely matter in determining the final outcome.

Byrne says leadership contestant Kellie Leitch is well-prepared for the get-out-the-vote (GOTV) portion of the race.

"In terms of ground organization, she's probably got the most effective team in terms of the GOTV mechanism coming up," she said.

As the voting draws nearer, many of the 14 leadership candidates have staked out controversial positions. Last week, Brad Trost's campaign said he's "not entirely comfortable with the whole gay thing," and referred to it as a lifestyle.

Byrne says Trost should be ignored.

"I don't think anyone looks at what Brad's saying as being serious. Brad said that for shock value, to have everyone respond exactly how they did -- with outrage," she said.

"Everyone should move on because our party is much bigger than this."