The federal NDP leader was passionate in his opposition to the Parti Quebecois government's discussion paper outlining its plans to ban public servants from displaying religious head wear and other symbols.
Describing the charter as a "dark cloud" hanging over multi-ethnic constituents in his own Montreal riding, Mulcair said it's those people who make him "emotional about somebody trying to use them for a political purpose."
"It has nothing to do with some high-sounding value. This has everything to do with the most base politics. It's undignified and we're going to fight it straight up," he said during a break from a two-day caucus retreat.
The show of emotion was in stark contrast to Mulcair's initial subdued, wait-and-see response to the charter when news of its contents first began leaking out weeks ago.
Outside Quebec, his comparative silence on the matter was contrasted unfavourably with Liberal Leader Justin Trudeau's immediate and repeated denunciations of the idea, prompting accusations that Mulcair was pandering to the NDP's nationalist base in Quebec.
A lukewarm response Tuesday would not have gone down well outside Quebec, where the NDP needs to make gains if it's to achieve its goal of winning power in 2015.
But his no-holds-barred denunciation could prove risky in Quebec, where polls suggest the charter is popular. The NDP's dream of forming government equally depends on hanging on to most of the gains made in the 2011 election, in which the party captured 59 of the province's 75 seats.
Neither the Conservatives nor the Liberals, which have only a handful of seats in the province, stand to potentially lose as much by taking a firm stand against the charter.
Mulcair shrugged off the polls, predicting that support for the charter will drop once Quebecers look at the text of what's actually being proposed.
"But you know what, even if (future polls) didn't show something different, I won't change my position. I don't take a position of principle based on what polls are telling me."
Mulcair said the text of the discussion paper "confirms our worst fears."
"We're categorical in rejecting this approach. Human rights don't have a best-before date, they're not temporary and they're not a popularity contest.
"To be told that a woman working in a daycare centre because she's wearing a head scarf will lose her job is to us intolerable in our society."
As a "rare" anglophone who managed to rise to the upper echelons of Quebec's civil service and as a one-time leader of an anglophone rights group before entering politics, Mulcair said study after study has concluded there is already "systemic discrimination" against minorities in the province's public service.
"What we have today is an attempt to impose state-mandated discrimination against minorities in the Quebec civil service. That for us is an absolute non-starter."
Mulcair repeatedly emphasized his 30-year experience fighting for minority rights in Quebec, in an apparent bid to underscore Trudeau's comparative lack of experience.
Indeed, the spirit of Trudeau seemed to be an unwelcome guest at the NDP caucus retreat, with Mulcair and his 99 MPs repeatedly fielding questions about how they intend to counter the threat posed by the popular Liberal leader.
Since Trudeau assumed the helm of the Liberals in April, his near-moribund party has vaulted into the lead in opinion polls, relegating the NDP to its traditional third-place slot.
New Democrat MPs maintained there's no need to panic; there's plenty of time until the next election to overtake the Liberals as long as the NDP remains focused on the real adversary — Prime Minister Stephen Harper's Conservatives — and the issues that matter most to Canadians.
"I think we need to stay true to our course," said Montreal MP Tyrone Benskin. "We are about substance, we're about getting the job done. We're not about sound bites and glory moments."
Hamilton MP David Christopherson acknowledged it can be difficult to fight against someone who is riding high, at least partially, on his famous family name. Trudeau's late father, Pierre, was a former prime minister.
"I know what it is to run against a dynastic name," said Christopherson who ran federally against Sheila Copps and municipally against her mother in Hamilton, where the Copps name is renowned.
"It's difficult. You can overcome it but, you know, there are some initial advantages and he's currently enjoying those initial advantages."
Having spent five months barely acknowledging Trudeau's existence, Mulcair has recently begun taking aim at the Liberal leader directly. He said Monday that he won't sanction negative personal attack ads against Trudeau but he won't shy away from ads that criticize Trudeau's record, his policies or what he called the Liberal party's history of promising one thing during an election and doing another afterward.
But the best thing New Democrats can do to counter the Trudeau threat is simply go back to basics, Mulcair said: knocking on thousands of doors, raising money, building organizations in each and every riding across the country.
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