Conservative leadership contenders will put their French-language skills to the test tonight in a high stakes and potentially humbling debate in Quebec City.

Thirteen candidates with proficiency ranging from beginner to bilingual will take the stage to square off over government, taxes, security and defence.

CBCnews.ca will carry the debate in French, starting at 6:30 p.m. ET.

Quebec Conservative MP Gérard Deltell, who has not yet endorsed any candidate, said the French-only debate is a clear indication the party believes the next leader must be bilingual.

He said tonight's forum will be crucial for helping establish who is best positioned to take on Liberal Prime Minister Justin Trudeau in the next election.

"What I want is someone today who can have conversations in French and in English with our party volunteers and things like that; maybe doing some interviews," he said. "But two years from now, I want a leader [who is] fluently bilingual, able to have a face-to-face debate with Justin Trudeau in French."

But there are mixed views on whether bilingualism is imperative in the Conservative leadership race, or critical to becoming prime minister.

Brian Lee Crowley, managing director of the Macdonald-Laurier Institute, believes that proficiency in French is of declining importance, as the rise of social media affords political leaders the ability to reach the electorate outside of traditional debates and mainstream media interviews.

Alternative channels

Politicians can be trained to deliver a few lines in French in a speech, and get their messages out in both languages through alternative channels.

"A politician who doesn't like what's being said in the mainstream media can make his own videos in his own controlled circumstances with language coaches and as many takes as he likes, then he can post it on social media and promote the hell out of it," he said.

Conservative leadership candidate Lisa Raitt is taking aim at two rivals, Kevin O'Leary and Kellie Leitch, accusing them of adopting Donald Trump-style tactics that could damage the party.

Crowley pointed to past prime ministers who were elected with little or no French-language proficiency, including Sir John A. Macdonald, William Lyon MacKenzie King, R.B. Bennett and John Diefenbaker. Today, bilingualism is still desirable but not a deal-breaker, he said.

Unilingual anglophone entrepreneur and reality show celebrity Kevin O'Leary came under fire from candidate Andrew Scheer for not declaring his candidacy before the French debate. Crowley said that strategy could work in his favour.

"Clearly he's made a calculation that it's better not to do it at all than to do it badly. Does that mean he thinks it's a deal-breaker? No, on the contrary, he thinks it's better not to do it at all."

University of Toronto political scientist Nelson Wiseman said while political Ottawa insiders think it's important to speak both official languages, most Canadians don't care. Even in Quebec, people care more about whether the politician is from the province than if they can speak French well.

The 14 participants in the Conservative leadership candidates' bilingual debate are seen in Moncton. (Andrew Vaughan/Canadian Press)

"It's a factor for Quebecers and for those Conservatives who are thinking about what will help them win seats in Quebec," he said. "But I don't think it's as big of a factor in that people think all political leaders need to be bilingual."

Wiseman said capacity in French is likely far less important for most voters than the image of the leader, their policy positions and party brand. But for political parties it can be deemed an asset because it can make a possible difference with that small percentage of people in a tight race.

Conservatives vote for a new party leader on May 27.

Tonight's debate moderator is Pascale Dery, a former journalist and news anchor who has hosted debates at universities and charity events. She also ran unsuccessfully under the Conservative banner in the last election.

Each candidate will make a 30-second opening statement in an order selected by random draw. Then, all​ 13 candidates will have a chance to answer every question to a maximum of 50 seconds.

Here are the participating candidates in order of podium position and opening remarks:

Chris Alexander.

Deepak Obhrai.

Michael Chong.

Erin O'Toole.

Kellie Leitch.

Andrew Scheer.

Pierre Lemieux.

Maxime Bernier.

Lisa Raitt.

Steven Blaney.

Rick Peterson.

Brad Trost.

Andrew Saxton.