Thomas Mulcair is driving some folks in Ottawa a bit nuts. It's getting harder to pigeonhole him, and pigeonholing is more or less the national sport of Ottawa.

Usually, he's portrayed in one of two ways: Angry Tom or Tough Tom. Angry Tom is hostage to a barely controlled, hair-trigger temper. Tough Tom is a composed and relentless prosecutor.

But to fairly assess his political prospects, avoiding these stereotypes is a good idea, because he's a far more nuanced personality. And as we head towards the next election, I'm betting that more facets of his personality will come into focus.

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Mr. Mulcair strikes me as someone very well aware of how he comes across, and there's every reason to believe he will be as diligent about this aspect of his leadership as he is other parts of his job.

He is a commanding presence in the House, using words sparingly and with explosive impact. His questions are a sort of political performance art. Less because of the logic or vocabulary on display, which can be impressive, and more because of his knack for finding a compelling tone of voice.

At times stern, outraged, disbelieving or sarcastic, Mr. Mulcair's rhetorical skills are putting food on the table for the NDP right now. And he feeds off his best performances, improving over time.

True, he gets angry. But what seems angry to one set of eyes might seem authentic to another. And voters who crave authenticity are more willing to overlook faux pas.

His appearance at a House of Commons committee a short while ago was a good opportunity to see a display of both his jousting strengths and occasional tonal weaknesses. The Liberals and Conservatives on the Committee were delighted at the opportunity to hold the NDP to account for their use of public funds on what seem like partisan purposes. But as geared up as his opponents were, the NDP Leader himself was pretty ready for the scrap.

Watching his work that day was a bit like watching a knuckle ball pitcher. When his pitches worked, they were impressive to watch, and more or less untouchable by his opponents. But at other moments, he looked extraordinarily hittable – tossing pitches that would be a problem for him in an election campaign.

He wandered back and forth across the line that separates splendid politics from self-immolation. When politicians stay on one side of the line we notice their best qualities: mental agility, clarity of thought and sense of humour. A short trip over the line and the same individual comes off as rude, superior, sarcastic and unlikeable.

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In recent months, there's been some evidence of a shift in Mr. Mulcair's style, an effort to shed the Angry Tom brand. At this year's Parliamentary Press Gallery Dinner, his speech was the evening's highlight – largely because he poked fun at himself, and seemed at ease doing so.

One of the more inaccurate truisms about politics is that "nice guys finish last." Given a choice, voters would rather be charmed than frightened. They won't pick someone charming if they believe that person will be incompetent. But if they judge all other factors more or less equal, then decency, humility and a sense of humour can be an important advantage.

In sum, Mr. Mulcair can play the heavy quite well, but he can also be effective at employing a lighter touch. While he may hear advice to stick with what has worked so well, to leave no skin on his opponents, no anger in the tank, my guess is he will know it's not the best advice. His opponents should not underestimate Mr. Mulcair's determination to shed the caricatures and adapt and improve his already impressive skill as a communicator.

Bruce Anderson is the chairman of polling firm Abacus Data, a regular member of CBC The National's "At Issue" panel and a founding partner of i2 Ideas and Issues Advertising.