"The longer I'm prime minister ... the longer I'm prime minister." Stephen Harper heads up the longevity chart. He's pictured here winning in 2008. Photograph by: Leah Hennel/Calgary Herald , Postmedia News

He has had the benefit of a weakened and divided opposition, its electoral force blunted by centre-left vote-splitting. His government, unlike those of most developed countries, has overseen a relatively stable national economy and ably weathered a global recession.

But whether by political genius, dumb luck or a combination of the two, Stephen Harper has proven — in purely objective terms, from a historical perspective — that he has prime ministerial staying power.

Harper, who has passed the eight-and-a-half year mark in Canada’s top political post — and ranks ninth on the list of longest-serving prime ministers — is on the cusp of leapfrogging three of those predecessors to the No. 6 spot, and becoming second only to Sir John A. Macdonald among 13 Conservative PMs in time spent at the helm of the nation.

So when Harper (as he surely will) personally leads Canadians in celebrating the 200thanniversary of Macdonald’s birth this coming January, he’ll do so possessing a newfound political kinship with the leading Father of Confederation and Conservative party patriarch.

By mid-September, according to the Canadian government’s official time-in-office listing, Harper will move up to eighth, passing post-war Liberal Louis St. Laurent. Then, within a stretch of nine days in November, Harper will overtake Conservative/Unionist Sir Robert Borden, and Conservative Brian Mulroney to stand sixth.

It would take Harper until March 2016 to pass Liberal rival Jean Chrétien.

“Length of time in office is a serious measure of effectiveness — I don’t think there’s any doubt of that,” says Canadian political historian Jack Granatstein, co-author with Norman Hillmer of the 1999 bestseller Prime Ministers: Ranking Canada’s Leaders. “You have to keep winning elections. You have to keep your party quiet, happy and satisfied. And you have to manage the affairs of the country and its dealings abroad. Anyone who can do that for almost nine years is somebody who is very effective. It doesn’t mean you’re popular — God knows the dislike of Harper is extreme and widespread — but he is effective. He keeps winning elections, and that’s the test.”

Harper became the country’s 22nd prime minister on Feb. 6, 2006, two weeks after his party won a minority mandate in the Jan. 23 general election. He is expected to remain prime minister until at least October 2015, when the next federal election is scheduled under new fixed-date rules — though an earlier vote could be called at the Conservative government’s discretion.

Harper’s imminent outdistancing of St. Laurent, Borden and Mulroney to join the upper echelon of prime ministerial endurance follows last year’s publication of an award-winning book by senior Maclean’s political writer Paul Wells, The Longer I’m Prime Minister: Stephen Harper and Canada, 2006-, which highlighted the significance Harper attached to mere survival in office for as long as possible — especially during the fragile early phase of his time as PM — to simply get Canadians accustomed again to the idea of a non-Liberal government.

The stay-in-power-at-all-costs strategy, Wells recounted, led the Harper Tories to avoid blundering into or orchestrating an early election during their first minority mandate, and was encapsulated in a line Harper is said to have repeated regularly to those in his inner circle: “You know, the longer I’m prime minister … the longer I’m prime minister.”