OTTAWA - Electoral co-operation between Liberals and Greens could be a "game-changer" that ensures defeat of the Harper Conservatives — even if New Democrats refuse to go along, Grit leadership hopeful Joyce Murray says.

NDP Leader Tom Mulcair has flatly rejected any kind of collaboration with the Liberals, whom he deems untrustworthy.

But Murray thinks Mulcair could still change his mind, persuaded by the many New Democrats — including House leader Nathan Cullen — who support co-operation.

Even if he doesn't, the Vancouver MP said that wouldn't cripple her proposal for a one-time non-compete pact among progressive parties in vulnerable Conservative ridings during the 2015 election.

The Liberals could still join forces with the Greens, whose leader, Elizabeth May, is an enthusiastic advocate of the idea.

"If necessary, yes, of course, we could do this with just the Green party," Murray told The Canadian Press in a wide-ranging interview, adding that May has told her she's interested in exploring the idea with her.

"I haven't crunched the numbers but I think that would be a game-changer as well."

A Liberal-Green united front during last November's byelection in Calgary Centre could have prevented Conservative Joan Crockatt from eking out a narrow victory with just under 37 per cent of the vote, Murray said. The Liberals took almost 33 per cent and the Greens 25 per cent, enough to win if — and it may be a big if — their votes had combined behind a single candidate.

On a national scale, however, it would be difficult for the Liberals and Greens, without the help of the NDP, to unseat the Conservative government. Based on the 2011 election results, a combined Liberal-Green vote could have theoretically defeated the Tories in just over a dozen ridings — not enough to defeat the governing party, although sufficient to reduce it to a minority.

Still, Murray is optimistic the NDP might yet come on board. She said Cullen, who ran third in last year's NDP leadership contest on an electoral co-operation ticket, congratulated her for launching her own campaign with a similar central plank.

She suggested Mulcair might eventually succumb to pressure to co-operate if the Greens and Liberals commit to do so.

"A lot can happen between now and the next federal election and I wouldn't exclude the possibility of an openness to this on the NDP's front," she said.

She added that Mulcair could face a backlash among the 18 million Canadians who didn't vote for the Conservatives and who "wouldn't be very happy to have one party decide not to co-operate in constructing a plan to have a single, progressive contestant in those ridings."

Murray is the only one of nine Liberal leadership aspirants to support any form of co-operation with other opposition parties. Her rivals — most of whom appear to be tilting right in a bid to woo back so-called business Liberals who've defected to the Tories — have adamantly ruled it out.

Murray believes her strategy makes more sense for a party groping for a path back to contention.

"I think there's a lot more Canadians that would like to see Stephen Harper defeated than there are Canadians who voted for him and would return back to the Liberal party."

Under Murray's co-operation proposal, each party would nominate candidates in every riding across the country. However, in ridings where the Tories won with less than 50 per cent of the vote, she'd allow local riding associations to choose to hold run-off nominations among the so-called progressive candidates to select a single contestant to square off against the Conservatives.

Murray's objective is not simply to defeat the Tories; it's to elect a majority of MPs committed to reforming Canada's electoral system to ensure future elections more accurately reflect each party's share of the popular vote. Under the current first-past-the-post system, parties routinely win the majority of seats in the House of Commons with less than 40 per cent of the vote.

"Our current system is very unrepresentative ... It is rewarding the very (negative, partisan) behaviour that is giving Parliament a bad name."

Murray is not advocating any specific reform. She'd set up a blue-ribbon panel or royal commission to examine alternatives and make recommendations, which would be put to a "public review," possibly a referendum.

Should she win, Murray allowed that Harper would doubtless demonize her proposal as the first step toward forming a coalition government — a club with which the Tories successfully beat the Liberals during the last election, even though coalitions are a perfectly legitimate option in a parliamentary democracy.

The fact that Harper was willing to "deliberately provide false information about how our democratic system works" illustrates why he must be defeated, Murray maintained.

"I mean, the kind of apathy and disengagement that results when people don't trust their political leaders is unhealthy for Canada, it's unhealthy for our democracy." she said.

"What's the difference between a successful state and a failed state like the Democratic Republic of Congo? Research shows that the health and strength of the democracy is a critical factor in the success of the state ... so we cannot go down this pathway of eroding people's trust in their elected representatives and their democracy and then disengaging.

"It's a dangerous route and we're on that path under the leadership of this prime minister."

Murray, a former British Columbia environment minister, said she's similarly prepared to defend her belief that Canada urgently needs to impose a price on carbon, through a carbon tax or cap and trade system or both — another politically risky idea the Tories have vilified as "a tax on everything."

"The purpose of government is to protect the common interest and the common good ... and we can't do that without having adult conversations about what's in the public interest. I'm not going to shy away from this conversation," she said.

Murray also said Canada's tax system needs "a holistic review," with an eye to shifting taxation to "harms, not goods" — hiking taxes on pollution, tobacco and marijuana, which she would legalize, for instance.

While she normally appears earnest and serious, Murray revealed a lighter side during the interview, showing off her skill as a juggler. She disclosed that her "first paid gig" was as a teenage juggler at a medieval fair in Vancouver. She continues to juggle to this day, saying it's a great stress reliever.

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