The famously nonpolitical Mr. Harper has already been through at least two incarnations since his return to public life. He was originally presented, at least in the media, as the Alberta isolationist and ideological purist who would lead the Canadian Alliance back into the right-wing laager. If it wasn't a fair portrait, it wasn't completely unfair either, and probably did much to cement Mr. Harper's appeal among the Alliance base.

With the leadership race more or less in the bag, candidate Harper then embarked on a much more interesting course. To be sure, his centrepiece opposition to a merger with the Conservatives was a tonic for a party that had very nearly collapsed in the wake of the Stockwell Day debacle. As Mr. Harper said over and over in his speech to the party convention this spring, "the Canadian Alliance is strong, and it is here to stay." But it was his reasoning that was so intriguing. It wasn't just that the endless rounds of reinvention to which the party had been subjected in recent years had sapped its strength and distracted its attention, or that negotiations with the Tories had proved fruitless. It was that the entire effort to "unite the right" was misdirected.

It was to be doubted whether the Tories were even on the right, for starters. And besides, there were many more voters to be found among centrist Liberals, especially in suburban and rural Ontario: the same folks who had been electing and re-electing Mike Harris's provincial Tories -- or the Liberals, for that matter, whose policies in the mid-1990s were borrowed holus-bolus from Reform.

This was new. If a Red Tory had said this, it would have been the same old "govern from the middle" blather, watering down the party's policies in order to make them more palatable to moderate voters. Mr. Harper's innovation was to see that the centre ground of Canadian politics had in fact shifted in the Alliance's direction, at least with respect to the party's core message of fiscal responsibility and democratic accountability.

Gone was the bitterness of the 2000 election's aftermath, when Mr. Harper and others were putting the Alliance's failure to break through in Ontario down to anti-Western bigotry. Now he could see the defeat's true causes: a poor campaign, and a general lack of professionalism. Ontario voters, he reminded Alliance members, will not vote for a protest party. They know their vote will decide things, and they need to see you are ready to form a government before they will even put you on their short list.

What is more, they need reassurance that you will not give away the store: to the provinces, to Quebec, to your own party's fringes. So Mr. Harper, already looking beyond the leadership race, let his latent Trudeauism show. He defended the Charter of Rights, and distanced himself from the party's social conservatives. He talked of invoking the federal trade and commerce power to force the provinces to adhere to the economic union. And, most critically, he renounced three decades of conservative thinking on Quebec, declaring an end to attempts to cozy up to Quebec nationalists in favour of a strongly federalist position.

There was in this the needed bridgehead to Ontario, based on what I call Trudeau Reformers: fiscally conservative, socially liberal, and aching for a more principled, more democratic politics. Even the Harper persona -- intellectual, unbending, a little aloof -- seemed to tap into this.

But that was then. What have we seen since? Mr. Harper has jettisoned both of his previous incarnations, whether as right-wing ideologue or neo-centrist, in favour of yet a third. Indeed, the person he most resembles these days is Preston Manning, whose flexibility on questions of principle so antagonized him.

On union with the Tories, Mr. Harper's position has now undergone a complete 180- degree shift. The quickie offer to Joe Clark soon after he assumed the leadership -- combining forces in the House, and joint candidates at the next election -- could be put down to tactical manoeuvring and was probably a bluff. But his latest venture, issued the day Mr. Clark announced his eventual resignation, goes much further. A joint leadership race? The Alliance and the Conservative party to be dissolved into some new entity? Isn't this where Mr. Manning left off?

On Quebec, similarly, the federalist tilt proved short-lived. No sooner had the neo- nationalist Action Democratique won a series of byelections this spring than up popped Mr. Harper, declaring that the ADQ and the Alliance were natural soulmates. Granted, the ADQ these days swears off constitutional change -- it can read the polls, after all -- but this is the party whose founding document was the Allaire report, and whose leader, Mario Dumont, voted yes in the 1995 referendum.

So I ask again: What has happened to Mr. Harper? Has he changed? Have circumstances?

Or has he been kidnapped and replaced by an impostor?