Conservatives are starting to feel bullish about vote-splitting.

Until recently, the ability of New Democrats to pull votes away from Liberals was a source of consternation for Andrew Scheer’s party. If Jagmeet Singh didn’t get his act together, it might be too easy for Justin Trudeau to rally the centre-left behind him, and take a big enough share of public support to block the Tories’ path to power.

Now, another party seems to be changing the equation. Even before this week, Conservatives were wondering aloud if the Green Party – coming off a string of seat pickups by its provincial cousins – might be as useful as the NDP in providing an alternative for voters who cast ballots for the Liberals in 2015.

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Such talk is increasing after the Greens’ impressive by-election win in British Columbia’s Nanaimo-Ladysmith riding earned them a second seat in the House of Commons. It will reach fever pitch if Elizabeth May succeeds in wooing Jody Wilson-Raybould and Jane Philpott, the dissident former Liberal ministers who seem to be flirting with running for her party.

The Tories are right to feel encouraged about the landscape. They face little competition for right-of-centre voters, save for Maxime Bernier’s People’s Party, which is polling in the low single digits and looks increasingly desperate to get anyone to pay attention to it. Meanwhile, if the Greens surge and the NDP doesn’t totally collapse, there will be a couple of serious options for Canadians who would not vote Conservative, but are disillusioned with Mr. Trudeau.

But there is one big question that should still give Conservatives pause as they look ahead to vote splits, and that complicates matters for anyone else trying to make sense of a crowded field: How much are parties, other than the ones led by Mr. Scheer and Mr. Trudeau, prepared to run national campaigns?

As usual, only one major party – the Bloc Québécois – will acknowledge publicly to not doing so. (Whether the Bloc proves resurgent is among the wild cards in the coming campaign, and it’s unclear whose expense that would be at.) But the current state of the Greens and the NDP suggests that they, too, may zero in on a relatively few regions.

For the Greens, it’s about scale-up capacity.

In the past general election, they campaigned effectively in a single riding, where Ms. May became the first MP elected under their banner, but scarcely anywhere else.

This campaign, they should be able to do more. But while the Greens set a personal best by fundraising nearly $800,000 in 2019’s first quarter, they’re still nowhere near the same ballpark as the Tories or Liberals in what they can afford to spend. Nor do they have large teams of experienced staff and volunteers, reams of voter data, or hundreds of well-vetted candidates. It would be a big victory to reach the dozen seats needed for official party status, and they are likely to focus their resources in a few areas – especially Vancouver Island, and places where provincial Greens have established beachheads, such as corners of Atlantic Canada.

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For the NDP, it may be more about scaling down.

It should manage a more typical national campaign than the Greens. Unlike Ms. May, who limits air travel for environmental reasons on top of financial ones, Mr. Singh will presumably run a busy cross-country tour. And his party has far more accumulated resources.

But unless their fortunes significantly improve in the next few months, it may be the narrowest national campaign the New Democrats have run since before Jack Layton was their leader. Their recent fundraising totals are not much higher than those of the the Greens, and even a $12-million mortgage on their headquarters probably won’t let them spend near the roughly $30-million they did in 2015. Theirs has the makings of a save-the-furniture campaign – one that might feel, some New Democrats quietly suggest, more like 30 or 40 by-election races than an ambitious general one – as they try to help incumbents hang on, and compete in a handful of other ridings.

In other words, there will likely be many places where Canadians never see a Green or NDP advertisement, candidate or volunteer.

Money and on-the-ground organization are not the be all and end all. Even where they’re non-competitive, parties’ messaging will reach some voters, through digital or traditional media, including leaders’ debates. And the New Democrats or Greens could catch a wave and suddenly be relevant in ridings where they lack presence, as with the NDP in 2011.

But the Conservatives probably shouldn’t count on that.

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That there is only one serious party on the centre-right, and now three on the centre-left, is a nice luxury. It can also be a trap, if they keep buying into an idea – which took hold under Stephen Harper’s leadership – that they’re effectively limited to under 40 per cent of the electorate, and need to mostly focus on maximizing their vote efficiency while hoping things break the right way.

The more they broaden their own universe, trying to appeal to a bigger plurality or majority of voters, the less they’ll have to fret about how much they’re helped by smaller parties that are their ideological opposites, and that have their own election imperatives to worry about.