MONTREAL -- Liberal Party Leader Justin Trudeau changed tactics Thursday night at the French-language leaders' debate, acting calmer and interrupting his opponents much less than he did during the first two English-language debates of the election campaign.

Trudeau stuck to talking points during the debate, hammering home his party's platform of cutting taxes for the middle class and paying for this by raising taxes for the highest earners. He also mentioned several times his pledge to increase benefits to families with children by cutting them for families making more than $200,000 a year.

Trudeau did not often cut his opponents off, instead waiting patiently to have a turn to give ready-made, clear and short responses.

One of the most heated issues was the question of whether people should be allowed to wear veils during citizenship ceremonies.

Trudeau let Conservative Leader Stephen Harper and NDP Leader Tom Mulcair yell at each other over the subject. His answer: "I think that if a man can't impose his will on how a woman should dress, we shouldn't let the state impose how a woman shouldn't dress."

Harper and Bloc Quebecois Leader Gilles Duceppe oppose allowing veils during the ceremony, while Trudeau, Mulcair and Green party Leader Elizabeth May do not.

Most leaders refrained from taking direct shots at Trudeau, but he got some jabs into his opponents, particularly Mulcair. He said the New Democrat wanted to give transfers to the provinces but with strings attacked -- a line that works in Quebec, a province weary of a strong central government.

"It's surprising that the NDP wants to act like a centralizing government," Trudeau said.

Trudeau also talked about his plan to run three years of what he called "modest deficits" of $10 billion in order to invest in infrastructure.

Mulcair said Trudeau's plan would put debt on the backs of future generations.

Trudeau shot back saying, "A new Metro isn't debt, Mr Mulcair."

The Liberal leader, on the question of infrastructure, said: "We need a partner that invests and that's what we are proposing. The others say balanced budgets any price -- and the austerity that comes with it."

The word austerity has a special ring in Quebec, a province that has seen thousands of people protest the provincial government's plan to cut public spending in hopes of balancing the budget.