Interim Conservative Leader Rona Ambrose says the race to replace Stephen Harper is "wide open" because there is "no big name" currently in the running.

"We could have as many as a dozen caucus members running for the race, and frankly, it's a wide open race because there is no big name, known person that has put their name forward, at least to this point," Ambrose said in an interview at Stornoway, the Official Opposition leader's home in Ottawa.

Peter MacKay, Jason Kenney and James Moore, prominent ministers in Stephen Harper's cabinet, have all decided against a bid for the party's leadership. MacKay, who had a strong lead in early polling, made his decision this week ahead of the Conservative caucus meeting in Halifax, paving the way for other entrants.

Maxime Bernier, Michael Chong, Tony Clement and Kellie Leitch, all of whom have previously served as ministers of the Crown, have formally put their names in the mix.

Former House Speaker Andrew Scheer is also expected to throw his hat in the ring, and is said to have strong support from his caucus colleagues.

'If there's no rubbing, there's no racing'

Leitch, who leads other candidates in the fundraising race, has already ignited debate about Canadian identity, proposing a test of sorts to weed out would-be immigrants who do not adhere to "unified Canadian values."

The proposal has sparked criticism from some of her colleagues — notably Chong — who have questioned both the desirability and feasibility of such a test.

"I will be the leader of the party in May of 2017, and it's because I'm talking about the issues that Canadians care about: about Canadian values," Leitch told reporters this week, when asked about criticism from her competitors.

Leadership hopeful Kellie Leitch arrives at the national Conservative summer caucus retreat in Halifax on Tuesday, Sept. 13, 2016. The two-day event will allow the party to prepare for next week's return of Parliament. (Andrew Vaughan/Canadian Press)

Ambrose, too, has raised red flags about Leitch's proposal, but the Alberta MP said she hopes the race is very competitive, and that all sorts of ideas are "highly and well debated."

She said disagreements, debate and discord between candidates is to be expected in any political race.

"As I jokingly said the other day, as they say in Talladega Nights, 'If there's no rubbing, there's no racing," she told Chris Hall in an interview for CBC Radio's The House, referencing the Will Ferrell film. "I'm sure there will be times when there is friction."

The contenders

Those who have declared and registered: Maxime Bernier; Michael Chong; Tony Clement; Kellie Leitch; Deepak Obhrai.

Those who have declared only: Dan Lindsay; Pierre Lemieux; Adrienne Snow; Brad Trost.

Expected to declare soon: Andrew Scheer.

Others who have mused about running but not declared: Steven Blaney; Kevin O'Leary; Erin O'Toole; Rick Peterson; Lisa Raitt.

While the debate over identity rages on around her, Ambrose said she is principally focused on holding the government to account on its economic performance — an issue she believes resonates best with ordinary voters.

"At the end of this, whoever wins is the person that has to resonate not just with people that hold a membership, they have to resonate with Canadians from all across the country, and I keep reminding them of that and reminding our caucus that our number one job, aside from the leadership race, is to stay squarely focused on the things that matter to ordinary working people," she told Hall.

There will be five party-sanctioned leadership debates in total, with the first scheduled for November 10 in Saskatoon. The second, a bilingual debate, will be on December 6 in Moncton.

No more Harper, Kenney​

Ambrose was first elected as an MP for Edmonton in 2004 and thus has spent all of her time in Parliament serving alongside the likes of Stephen Harper and Jason Kenney, both of whom announced this summer they would be leaving federal politics.

Asked if she thought their departures were a sign of the dawn of a new era in Conservative politics, she said, "I think it might be.

"There's so many new faces when I look around our caucus, and I'm excited about that," she said. About a third of the 99-strong Conservative caucus consists of rookie MPs, including a healthy contingent of new Tories from Quebec.

Stephen Harper speaks with Jason Kenney at a campaign stop in Markham, Ont., during the 2015 election campaign. (Canadian Press/Sean Kilpatrick)

These fresh faces are spearheading modernization by launching new policy discussions the party has avoided in the past, she added.

"Some of them, sometimes, are uncomfortable, but I think it's important for the party to have those discussions."

She said she and others will miss both of these Tory stalwarts, but she endorsed Kenney in his push to unite the provincial right in Alberta.

Follow CBC Radio's The House on Twitter: @CBCTheHouse. Follow J.P. Tasker on Twitter: @JPTasker