Peter MacKay, one of the people who helped create the modern Conservative Party, says positions on immigration from one leadership candidate may damage the party's brand.

MacKay was asked what he thought about Kellie Leitch's policy to screen immigrants for what she terms "Canadian values."

The question of what are Canadian values is far from clear, MacKay said.

"When you drill down into that type of discussion the first question that comes to mind is, who makes that decision? And what is that bar going to be? And how possibly could somebody coming from a country that has no understanding of what it means to be a Canadian meet that criteria?"

The former leader of the Progressive Conservative Party helped unite the party with the Canadian Alliance to become the Conservative Party. He decided not to run for the leadership last September and has rarely weighed in on the race since announcing that decision.

Kellie Leitch says it's OK if other members of the party criticize her demand for a 'Canadian values' test, as she believes Canadians are behind her. (Andrew Vaughan/Canadian Press)

He says he's concerned for the long-term health of the party.

"As somebody who has invested a lot of time and effort into building this party and putting us in contention and somebody who cares deeply for the country, you need competitive parties. You need, in my estimation, a Conservative party that is vying for government," he explained.

"I do worry about certain positions that have been staked out. Having been through a leadership contest, I know that the rhetoric sometimes gets heated, but it does pose the risk of causing brand damage for the Conservative Party," MacKay added.

Fellow Conservatives among Leitch's critics

His comments come a few days after the Nova Scotia leader of the Progressive Conservative Party condemned Leitch and Stephen Blaney for their positions on immigration, arguing they were not inclusive enough.

When asked by reporters, Leitch says no one at the debate raised the criticism with her.

Her campaign manager stepped down last week, saying he felt he was becoming a distraction to her campaign. Nick Kouvalis apologized after insulting a constitutional expert on Twitter, using the term "cuck" associated with the far right in the U.S.

But Leitch insists all this criticism is not hurting her campaign.

"No, what I found is that a number of individuals are looking at exactly what my policy is about, so they understand it better. And I'm encouraging individuals to not have a filter of others or the media, to go directly to my website and hear in my own words what I've been talking about," Leitch said after the debate.

But other leadership candidates continued to criticize her stand on immigration, arguing it could hurt the party in 2019.

"I believe it's very important for the leader of our party to not do or say anything in this leadership race to give them an edge, to help them sell a few more memberships, but ultimately damage our party's brand in 2019," Andrew Scheer told reporters.

Candidates participate in the Conservative leadership debate in Halifax on Saturday. Leadership hopefuls Lisa Raitt and Andrew Scheer criticized Leitch's stand on immigration, arguing it could hurt the party in 2019. (Andrew Vaughan/Canadian Press)

Lisa Raitt has said in the past she does not agree with Leitch's proposal to interview every immigrant on Canadian values.

"I don't agree with Kellie's policy on values testing... So I'm going to say those things when I think that they're going to be a problem to get elected," she said.

Leitch seemed unmoved by the criticism.

"If other candidates don't agree with me on that, that's perfectly fine, because the majority of Canadians are with me," she said.

MacKay on O'Leary: 'Commit first ... to Canada'

The newest candidate in the race faced some tough questions this weekend too.

O'Leary shows 'horrific lack of judgement,' says Michael Chong 2:33

A CBC News examination of Kevin O'Leary's media appearances and social media postings suggested that five or six days of his first week of campaigning were spent south of the border in New York City and Florida.

O'Leary was unapologetic.

Kevin O'Leary is flanked by Steven Blaney, left, and Kellie Leitch at the Conservative leadership candidates' debate, in Halifax on Saturday. He says he's speaking up for Canadian interests when he's travelling in the U.S. (Canadian Press)

"I'm actually a household name in the United States as you know, and because of what's happening in trade and immigration I've become a spokesperson for Canada on American networks. I'm spending a lot of time in New York talking our case, preparing for what's going to happen in these negotiations, because Trump this morning announced he's prepared to tear up NAFTA," O'Leary said Saturday as he arrived for the leadership debate in Halifax.

MacKay isn't sure Conservatives will agree with O'Leary.

"I think Canadians expect that you're going to commit first and foremost to Canada. Just as a provincial premier is going to commit to their province. I think that's one of those baseline expectations that most Canadians, most certainly that I have talked to, would share," MacKay said.