HAMILTON -- Liberal Leader Justin Trudeau enlisted the support of former prime minister Jean Chretien on Sunday to brush up his economic bona fides and accuse the NDP of wanting to make it easier to break up the country.

Both Trudeau and Chretien told a rally Sunday in Hamilton that an NDP government would repeal the Clarity Act, which says any referendum requires a clear majority for separation.

Trudeau said NDP Leader Tom Mulcair believes a single vote -- 50 per cent plus one -- should decide whether Canada remains united, thereby resurrecting the ghost of a divided Canada not seen since the 1995 vote on Quebec secession.

"The divisions that referendum (sowed) and the pain that it caused Canadians must not be repeated," said Trudeau, standing alongside Chretien.

"Mulcair? He wants to roll the dice. He wants to put separation back on the table and turn the clock back 20 years, which means all of Thomas Mulcair's experience in politics has simply taught him one thing: to play politics with anything and everything, including the unity of this country to gain a few votes from separatists."

Mulcair has dismissed such criticism, saying he has fought for a united Canada his whole life but that the Clarity Act doesn't spell out what constitutes a majority.

"I'll let Justin Trudeau continue with his golden oldies tour and bring out Jean Chretien today and start talking about the quarrels of the past," Mulcair said earlier Sunday after making a seniors health-care announcement in Vancouver.

"We are talking about solving the problems for the future."

Chretien employed his trademark folksy style to reinforce Trudeau's message. He also told party supporters that it was past Liberal governments who restored prosperity after years of Conservative rule.

"Now Justin, you'll have to do the same thing for Harper," Chretien quipped.

He later set his sights on Mulcair's promise to balance the books within the first year of an NDP mandate.

"Come on," Chretien said to roars of approval. "Canadians, Mr. Mulcair, know how to add."

Trudeau has said a Liberal government would run deficits until 2019 while increasing infrastructure spending in a bid to spur economic growth.