Today’s fun fact, from “Moving Canada Forward,” the Liberal party platform: Over the next five years, the government of Canada will spend in excess of $1-trillion. That’s trillion—and it’s true regardless of which party is elected. The Liberals would spend $1-trillion, the Conservatives would spend $1-trillion, and the NDP—well, it would spend $2-trillion if it could, but there’s only room for so many windmills.

The differences between the parties, which everyone on all sides will spend the next three weeks trying to convince you are stark and extraordinary, are rounding errors set against that stark and extraordinary number: one trillion dollars. The era of big government never really ended in Canada, and no major party is proposing to change that much.

There are differences between the parties, of course, but only at the margin. Indeed, if the Conservatives were to win this election, it would be an odd sort of victory, since it would come at a time when all three major parties are moving sharply to the left.

The Liberal platform, with its $27-billion in new spending, is a clear attempt to corral the left-wing vote that has lately been straying into the NDP pen. But the NDP has its own left flank to worry about, with the emergence of the Green party as a serious electoral force; they’re in double digits in British Columbia, and even at 6% nationally, that’s a third of the NDP vote. So on top of the $61-billion already pledged in the NDP platform, Jack Layton promises to spend $10-billion putting up windmills all over Canada.

The Liberals chase the NDP, and the NDP chases the Greens. And the Conservatives? Suddenly, miraculously, they have been given a clear field. The party has spent the past several months grimly marching toward the centre, abandoning one right-wing nostrum after another in anticipation of a bloody battle for the middle ground—only to find the other parties have already given way. Where until lately it was the right that was split, the salient fact of Canadian politics is now the three-way split on the left—four, if you count the Bloc Quebecois. Or, at least, that is the appetizing prospect now opening before the Conservatives. But what happens next is very much up to them.

The Liberals won three straight elections by seizing the centre-right vote from the Tories, notably in Ontario. Not only did it win them a bunch of seats, but it knocked the mortar out of the Tory coalition; without Ontario, there was nothing to hold together the always fragile alliance of Western populists and Quebec nationalists that had carried Brian Mulroney to back-to-back majorities. There were other reasons for the fracture of that coalition, notably differences over Quebec’s constitutional status. (Another irony: Today it is the Liberals who are split on Quebec, and the Tories who are united.) But just as important a factor in splitting the right-wing vote were the policies pursued by the Liberals, starting with the historic 1995 budget.

People speak of the vote having been split between the two right-wing parties, just as the Harris Conservatives were said to benefit from a split of the vote between the Liberals and the NDP, without anyone noticing that in both cases it is the same group of voters we are talking about. How can the vote be split both between the right and the left? Because in each case the vote did not just split, it was the party opposite that did the splitting. Whether it was the Liberals in their first term or the Harrisites in theirs, in each case they defined and drove the agenda. When the other parties are put in a position of merely reacting, that’s when the vote “splits.”

That’s the opportunity for the Conservatives—and for Stephen Harper. To this point in the campaign he has mostly been playing defence. He toured Atlantic Canada explaining he was not anti-Maritimes. He toured Quebec explaining he was not anti-French. He toured the West explaining he was not anti-Canada. And in one policy area after another he has been snuggling up to the Liberal position. There isn’t a dime’s worth of difference between the two parties on health care, for example: The Liberals would give more billions to the provinces, whereas Mr. Harper would prefer to spend it on a national pharmacare program. (Indeed, so far as his tax cut is offset by provincial tax increases, as in Ontario, it amounts to a federal-provincial transfer by the back door.)

Tory strategy appears to be to position the party as the Liberals circa 1997—before the rot set in. Past Liberal statements are cited with alarming regularity, ostensibly to ward off charges of extremism but also, one suspects, in an effort at impersonation. In his Toronto speech on Wednesday, Mr. Harper several times quoted approvingly what the “old Paul Martin” would have said or done (clever that: not only does he suggest it is Mr. Martin who has moved off the centre ground, but he slips in a sly dig at his age).

That’s fine, as far as it goes. Voters have got the message that Mr. Harper is neither a hick nor a nutbar, aided by his unflappable performance so far in the campaign. (Defending his “firewall” comments: “Mr. Martin’s only problem seems to be when he’s speaking English … he has extreme difficulty with Alberta exercising these [jurisdictions], and when he’s speaking French, he seems to forget that Quebec already exercises many [of the same jurisdictions].” Unanswerable.)

But now he has to seize the initiative. Imitating the Liberals (minus the corruption) has carried the Conservatives this far. But as the Liberals move left, it is time for the Tories to start to mark out what distinguishes them, not just from the Liberals, but from the other three (four, if you count etc.) parties. Tax cuts may be the issue that does it. If the other parties are all opposed, then all that strenuous effort at “moderation” will have been worth something. The Tories, by defining the issue, will have captured the centre ground. The other parties, by uniting in their opposition, will have split the vote.