"Without putting too fine a point on it, I'm no Stéphane Dion or Michael Ignatieff, and people know that," Tom Mulcair said in the fall of 2013. "So does Stephen Harper. He's been getting the fight of his life in the House."

In an interview around that same time, the NDP leader put an even finer point on it.

"I don't shy away from a good tough debate, at all," he said. "It's always been part and parcel of my understanding of what we have to do in politics, because otherwise you end up like Stéphane Dion or Michael Ignatieff. You are just going to be roadkill."

So it turns out one can put up a fight and still get run over.

But two days after his fellow New Democrats made a dramatic show of backing over him, Mulcair appeared in the House of Commons, apparently determined to carry on.

And when the Speaker called on the member for Outremont to ask the sixth question of the afternoon, Mulcair was acknowledged with a standing ovation, not merely from his typically peppy caucus, but from Conservatives and Liberals as well, a seemingly unanimous expression of appreciation.

Admired in defeat

A politician is never more easily admired than in defeat or retirement. And probably no one appreciates the politician quite like another politician. Rejection, it might be noted, stalks them all.

"Mr. Speaker, after years of ethically challenged Conservative rule, the Liberals promised to do things differently," Mulcair began when everyone had returned to their seats.

The Conservatives theatrically groaned in jest. Mulcair laughed. Liberals stood to applaud.

"The minister of justice is doing certain things differently," the NDP leader continued. "When Conservative minister Shelly Glover was caught holding a dodgy fundraiser in 2013, she promptly gave the money back. However, this minister refuses to do the same.

"Will the prime minister ask his minister of justice to simply give the money back?"

Now the Conservatives stood to applaud.

The prime minister defended his government and Mulcair moved on to other suggestions of shortcomings. "The Liberals swore they would be different," he said, "but they keep finding novel ways of being the Liberals."

An hour later, Mulcair was back up in the House to speak on the budget, persnickety, sarcastic, patronizing and demanding as he alleged a dozen different ways the Liberals had failed in their fiscal plan (with a couple of asides for the Ontario government of Kathleen Wynne).

The Power Panel discusses Tom Mulcair's future and his return to the House of Commons. 10:21

The best since Diefenbaker?

Pending whatever the future holds for him, Mulcair will likely be remembered as a good Opposition leader, as limited a prize as that is — a vital role, the performance of which comes with no guaranteed reward. He was better at it than Dion and Ignatieff, though they had to deal with the trickier considerations of minority government. No less than Brian Mulroney called him the best leader of the Opposition since John Diefenbaker.

His dogged and prosecutorial questioning of Harper over the matter of Mike Duffy made for captivating theatre, prolonging and underlining a drama that sapped the sitting government's credibility. And his party was loud in its criticism of that government's anti-terror legislation, electoral reform and budget bills.

He is an imperfect politician, but he was perhaps a model of what the government's chief critic should be: easily unsatisfied, often fastidious and square-shouldered, well-suited to wearing and projecting furious indignation. But that is apparently not enough.

In that regard, the most withering criticism of the past weekend in Edmonton might have been Canadian Labour Congress leader Hassan Yussuf's suggestion that "progress and elections aren't won on parliamentary committees or in question period."

Even if failing to perform in Parliament might be grounds for disqualification.

Tom Mulcair returns to Question Period after losing the support of the NDP in leadership review in Edmonton 2:07

Opposition leaders who fell short

Only just about half of the two dozen full leaders of the Opposition since Confederation have proceeded from there to the prime minister's chair directly across the aisle. And Mulcair joins Edward Blake, George Drew, Robert Stanfield, Preston Manning, Dion and Ignatieff among those who didn't make it.

Maybe the Mulcair of the campaign needed to be more like the Mulcair of Parliament. But whatever the precise causes, he lacked the sort of mix of leadership, advisers, decisions, context and circumstance that periodically elevates someone to the top of the federal government.

That he tried to stay on, apparently in hopes of trying again in 2019, seems ill-considered now, but it was perhaps in keeping with the idea of him. It remains to be seen whether he can stay without awkwardness until a new leader is chosen, but there is something neatly stubborn about the attempt.

(Stanley Knowles, the semi-legendary New Democrat MP, was made an honorary officer of Parliament when he retired. Perhaps Mulcair could be made an honorary opposition leader, called on whenever the prime minister is particularly deserving of castigation.)

Constant climbing

Jack Layton used to say that the NDP was like the Dall sheep, a species common to mountain ranges. By Layton's telling, the sheep, like New Democrats, were used to facing an incline. "If you put us on a flat surface, we'd fall over," he once said. "We'd be in a completely foreign environment."

Insofar as Mulcair fell over once his party was no longer looking up at its rivals, he might have merely proved Layton prophetic.

And in his failure to transition from useful critic to government leader, Mulcair might have personified the story of the NDP to date.

It will be for his successors, as leader of the Opposition and leader of the NDP, to learn whatever they can from his example.