For years, the knock on the Green party has been that it splits the non-right-wing vote, enabling those most hostile to the environment to remain in power.
New Democrats, in particular, point to the long reign of the B.C. Liberals in B.C. and the Conservatives in Ottawa as proof of this hypothesis.
Each federal and provincial election is dissected by New Democrats for evidence that somehow a few hundred or a few thousand Green votes helped one of the planet killers come first past the post before a more progressive candidate.
Green party activists vehemently reject this claim. They point to ridings where they've succeeded to suggest that they actually hurt right-wing candidates more than anyone else.
The prime example is Green Party of Canada Leader Elizabeth May. She took Saanich–Gulf Islands from a Conservative cabinet minister, Gary Lunn.
Vancouver's only Green city councillor, Adriane Carr, topped the polls in the 2014 election in which the NPA only elected three members to council and lost the mayoral race.
B.C.'s only Green MLA, Andrew Weaver, defeated a B.C. Liberal cabinet minister, Ida Chong.
In all three of these elections, voter turnout increased significantly, in part because there were strong Green candidates in the race.
Of course, New Democrats can point to other examples to support their argument.
Greens had success in the last Vancouver park board election, yet the NPA took control of the board.
Meanwhile, a Green candidate, Janet Fraser, was elected to the Vancouver school board and threw her support behind the NPA in the election of a new chair. Vision Vancouver trustee Ken Clement narrowly lost the election, depriving his party of another majority.
In the last B.C. election, right-of-centre candidates won narrow victories in provincial constituencies such as Burnaby-North and Surrey-Fleetwood, further fuelling NDP claims of vote splitting.
In 2013, B.C. Liberal Richard Lee defeated the NDP's Janet Routledge in Burnaby-North by 668 votes. Green candidate Carrie McLaren captured 1,577 votes.
In Surrey-Fleetwood, B.C. Liberal Peter Fassbender beat the NDP's Jagrup Brar by 265 votes. Green candidate Tim Binnema attracted 1,032 votes and Conservative Murali Krishnan picked up 748.
So who's right? Could Green candidate Claire Martin, a well-known meteorologist, be the best bet in North Vancouver to defeat incumbent Conservative Andrew Saxton?
Or will another Green candidate, accountant Michael Barkusky, split the anti-Conservative vote in Vancouver Granville, enabling Stephen Harper's man, Erinn Broshko, to squeek out a victory with fewer than 40 percent of the votes?
And what about in Burnaby North-Seymour, where the Greens are investing their hopes and precious campaign resources in SFU professor Lynne Quarmby? The NDP has nominated a former provincial court chief judge, Carol Baird Ellan, to take on Conservative Mike Little and Liberal Terry Beech.
No one can deny that Green Leader Elizabeth May has done a tremendous job in elevating the importance of climate change on the national agenda.
She's accomplished this without much help from the mainstream media, which continues to downplay the importance of this issue.
Before May became Green leader, the NDP and the Liberals did not devote anywhere near as much attention to global warming as they do now.
Climate change was barely mentioned in the 2006 election that catapulted Harper into the prime minister's chair.
But still, there is this lingering question in the minds of many citizens: is a vote for a Green candidate really a vote for Stephen Harper?
In tonight's first televised national-party leaders debate, May will have to make the case that this isn't the case.
Otherwise, she risks seeing the Green vote evaporate in the rush to back whichever other party appears to be the best bet to throw Harper out of power.