MONTREAL — Tens of thousands of blue-collar workers from across Quebec — many of them bringing their children — marched through the streets of downtown Montreal on Saturday afternoon in the city’s noisiest demonstration since the student protests of 2012.

Organized by the Coalition pour la libre négotiation, the demonstrators were protesting against Bill 3, the proposed law that would hike their pension contributions to make up for deficits in many municipal plans. They blew horns and waved flags, marching from Lafontaine Park to Quebec Premier Philippe Couillard’s offices on McGill College Ave., where union leaders warned they won’t give up their pension rights without a hard fight.

“If you want a confrontation, you’ll get one,” one union leader shouted to roars of approval from the crowd.

Bill 3 has already resulted in a number of pressure tactics, including Montreal police officers swapping their uniforms for camouflage pants and the ransacking last month of city hall. That protest led to criminal charges being filed against 41 members of the firefighters’ union.

“Mr. Couillard, your social dialogue is nothing but an anti-social monologue, a boss’s discourse,” Daniel Boyer, president of the Quebec Federation of Labour, told protesters.

“One word: never. Never will we allow you to trample upon our pension rights. We have a pension plan that we want to keep. Every Quebecer has the right to live a pleasant life in retirement.”

To date, however, Couillard has said the government doesn’t expect to make major changes to Bill 3.