Stephen Harper's Conservatives say they will be a no-show at two federal political leaders' debates announced by major Canadian broadcasters Thursday.

CTV News, CBC News, Global News and Radio-Canada announced that they've reached agreement in principle with Justin Trudeau's Liberals, Thomas Mulcair's NDP, Elizabeth May's Greens and the Bloc Québécois.

"These debates, one in English and one in French, are to be held at the height of the 2015 federal election campaign," the consortium of broadcasters announced in a news release.

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The broadcasters also unveiled new partnerships with Google, Facebook, Twitter, Instagram, Vine and YouTube to help deliver their debates online and give them "unprecedented digital reach."

The Harper Conservatives have rejected debate proposals from the consortium and spokesman Kory Teneycke has said the party wouldn't entertain any more.

On Thursday, Mr. Teneycke stood firm on the matter, saying the Tories will not be participating in the consortium debates. "Our position hasn't changed. We agreed to do five [independently organized] debates. We've announced four of them. We're still looking for the final and fifth debate in French. We have declined a consortium proposal. Our position hasn't changed."

The Conservatives agreed most recently to take part in a federal leaders' debate on foreign policy organized by Toronto's Munk Debates.

"There are stark differences between Prime Minister Stephen Harper and the opposition leaders on foreign policy, including how to respond to Russian aggression in Eastern Europe, how best to combat the rise of ISIS, and the importance of expanding free trade around the world," Mr. Teneycke said Thursday. "We look forward to an in-depth discussion of Canada's foreign policy, as these issues have been treated as an afterthought in many previous election debates."

The Munk Debates are run by the Aurea Foundation, which is a registered charity established by Peter and Melanie Munk.

Gerald Butts, an adviser to Mr. Trudeau, blasted the Munk Debates as biased in favour of Mr. Harper.

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"Shockingly, Harper agreed to a debate sponsored by Peter Munk. Who's moderating? John Baird?," Mr. Butts wrote on his Twitter account Thursday. Mr. Baird is a former senior cabinet minister in the Harper government who now serves on the advisory board of Barrick Gold, a company founded by Mr. Munk.

‎There are now at least four independently organized leaders' debates in the works as the clock counts down to a federal election this fall. They include one hosted by The Globe and Mail, one by Maclean's magazine and another by French-language broadcaster TVA.

The Conservatives and NDP have accepted invitations to participate in the Globe, Maclean's and TVA debates. The Liberals have signalled their interest but are still considering their options.

The members of the traditional broadcasting consortium, for their part, say they're the only ones able to deliver the debates to the greatest number of Canadians. There's no word yet on whether they'll leave an empty podium to represent the Conservative leader at their debates.

One likely consequence of dividing up debates among various media outlets instead of allowing big broadcasters to host them is that the total audience size is at risk of being diminished.

The Conservatives say they're embracing independently run debates because they want more opportunities for freewheeling interaction between leaders than what they felt the broadcast consortium would offer. They're hoping to trip up rival Justin Trudeau in a format that allows more point and counterpoint between leaders.