This has been one great sprawl of an election, which has ricocheted from the great to the small, from the Duffy courtroom to the oath of citizenship, from minutely parsed debates to what seems a record rash of candidate gaffes. On the gaffe front, the parties have more or less inoculated each other — as soon as one party’s candidate had spoken the unspeakable or acted the unthinkable, there’s another from another party eager to offer a rival blunder. (Though the gentleman caught peeing in a coffee cup and dumping the ambrosia in a client’s kitchen sink has probably earned himself a special place in the history of election trivia.)

In the many weeks this campaign has already run, each stage of it has devoured the one before. I cannot, for example, imagine either of the opposition parties at this point running a blitz of “Duffy” ads, despite the remorseless fascination with the Senate case at the opening of the campaign.

Many millions have been spent, by each of the parties, presumably to underline a core message, to mark their respective leaders and their platforms as the ones worthy of sustaining the voters’ trust, and having the program that Canada needs for the next four or five years. Those millions spent may as well have been left in the war chest.

I think it’s very hard to believe that escalator ads, or “Just not ready,” or whatever the anti-NDP pitch has been, have had anything but marginal effect, pro or con, on the very limited pool of the easily influenced. I have the notion that much political advertising amounts to little more than invigorating the morale of supporters, rather than really trying to change the minds or dispositions of others. It reassures the legions of volunteers and campaign workers that their side is aggressive and confident, acts somewhat like a standard in battle — a summons to persist and offer greater effort by those on your side — more than working any active distress among one’s opponents. Ads may hold ground, they rarely take new territory. Save when they massively backfire, as in the infamous television spot, in the 1993 campaign, that overtly mocked Jean Chrétien’s appearance.

Despite its duration then, the ad campaigns, the flood of changing events and issues, this campaign has been remarkably contained by, or limited to (with one extravagant exception) the question of leadership.  And the leadership question is almost perfectly contained within the proposition of whether Stephen Harper’s time as prime minister is up. I dislike the cliché but he is the lightning rod of the entire campaign. His long tenure has sharpened the antagonism of those who have never supported him to exasperation point. His supporters have the fidelity of martyrs.

The only persistent emotion — not platforms or in any substantial sense ideas — that drives most voters is on the person and performance of Stephen Harper. Every element in this campaign gets played through the prism on where a person stands on the prime minister. That’s the theme and the engine that drives it, pro and con, of the coming vote.

The “extravagant exception” I referred to is, of course, what we’re calling the “niqab issue.” It is really quite amazing that a matter that may directly or actually refer only to one or two actual voters has exploded into the most dominating subject at the crisis point of a long campaign. The Trans-Pacific Partnership deal, which in normal times would itself be enough to fuel an entire election drive, appears to have almost footnote status compared to it. It has had the most potent impact so far of any issue. Many ascribe Mr. Mulcair’s current decline in Quebec to his strong stand on this.

It is not the actuality of the issue which gives it power, it is its symbolic reach. It opens the great themes of tolerance and respect, and where, or if, Canadians draw boundaries on those who wish to join our country.  It is a controversy too that speaks differently in different parts of the country. But most of all in the vote we are about to take the Conservative position — that of wanting to limit the veiled face — presents the face of the Harper government. Is forbidding the veil during the oath of citizenship a “protection” of the values of Canadian citizenship, or an “outrage” against its very meaning?

So at the end of this long sprawling campaign, more than any other consideration I can think of, that’s the vote driver. How voters view the niqab is very much a proxy for how they see the Harper government and its leader. Apart from everything else it is surely a very wonderful instance of how an element impossible to foresee, so very particular and limited in its actual impact, can occasion a crucial turn in a great national campaign.