OTTAWA - Green party Leader Elizabeth May has been shut out of the televised election debates after every major party but the Liberals shunned her inclusion.

TV network officials hinted that one or more of the other party leaders would have pulled out of the showcase election event, set for Ottawa on Oct. 1 and 2, if May had participated.

NDP campaign spokesman Brad Lavigne confirmed that Leader Jack Layton had refused to attend with May present.

All signs pointed to the Conservatives as being the other deal breaker.

"We believe that as someone who's endorsed (Liberal Leader) Stephane Dion to be the prime minister of Canada, she has endorsed Liberal candidates throughout the country," Lavigne said.

"We said that if the Liberals were going to have two representatives, we would not accept the invitation."

Dion said he welcomed May, the only woman leading a federal party in the election, to join the debates.

Jason MacDonald, a spokesman for the network consortium, said the other three parties all opposed her participation "and it became clear that if the Green party were included, there would be no leaders' debates.

"In the interest of Canadians, the consortium has determined that it is better to broadcast the debates with the four major party leaders, rather than not at all."

The nationally televised event is run by Canada's major TV networks through an umbrella group that decides who takes part. The consortium includes CBC, Radio Canada, CTV, Global and TVA.

Bloc Quebecois Leader Gilles Duceppe stressed that he never threatened to cancel, although he'd prefer the debate be restricted to leaders of the four major parties in Parliament.

But Prime Minister Stephen Harper, like the NDP, said Monday that May's inclusion would in essence allow a second Liberal candidate.

He said May's platform is similar to Dion's and that she will ultimately endorse the Liberals.

"Elizabeth May is not an opponent of Stephane Dion," Harper said at a campaign event in Richmond, B.C.

"She is his candidate in (the Nova Scotia riding of) Central Nova, and I think it would be fundamentally unfair to have two candidates who are essentially running on the same platform in the debate."

Dion raised eyebrows by opting not to run a Liberal candidate against May. She in turn has upset some Greens by heaping praise on Dion's environmental record and touting him as a better prime minister than Harper.

Still, she insists she is a party leader in her own right and dismissed any notion that she will endorse the Liberals as "nonsense."

May threatened to go to court over Monday's decision, accusing the TV networks of "old boy" tactics as she squarely blamed Harper for her exclusion.

"I think Mr. Harper's role was determinative," she said in an interview. "He was the only one making the (public) case that I was not allowed to participate.

"In the interest of fairness ... and a full and fair election, the Green party will seek the guidance of the Federal Court in terms of ... how manipulated the public airwaves can be by the objection of a prime minister who doesn't want to face me in the debate."

Harper had made no further comment on the matter by Monday evening.

In the past, the courts and federal radio-television regulator have washed their hands of the matter, saying it's up to the broadcasters to decide who can participate in an event that can change the course of election campaigns.

The Green leader has stepped up pressure on the networks ever since an Independent MP joined the party, giving the Greens a temporary toehold in the House of Commons.

"I believe the consortium has been overly influenced by hints, and threats without actually having public statements on the record from any national party political leader that they would actually refuse to participate in the debates if I was included," May said.

Layton was hustled away by handlers when reporters tried to clarify if he had said he would pull out.

"I'm looking forward to debating the prime minister," was his only comment.

Before Lavigne spoke, another NDP official speaking off record said that a negotiator for Layton had told network organizers that he would have to "reconsider" his participation but had not threatened to boycott.

Dion told a campaign rally in his Montreal riding of Saint-Laurent on Monday night that May should have been included.

"It's about fairness. Elizabeth May should have been part of the debate. Period."

Most Canadians will find her exclusion "deeply anti-democratic, whether they plan to vote Green or not," May fumed. Especially galling, she said, is the fact Duceppe is allowed in even though voters outside Quebec can't vote for his party.

"They can vote for the Green party in all 306 ridings across Canada. They want to know where we stand."

She says Harper's bid to freeze her out has more to do with concern that the Greens could eat into Conservative support.

It's also the latest in a string of actions that suggest Harper's distaste for women's full equality and a dislike of feminists in particular, she charged.

Pollsters have repeatedly cited as a potential weakness the Conservative failure to sway female voters.

"I think it's because (Harper) removed from the mandate of Status of Women Canada achieving equality for women," May said.

"I think it's because he cancelled universal child care when it was within our grasp. I think it's because women look at him and realize that here is someone who really does have a deep antipathy for the aspirations of many Canadian women for full equality, full participation."