Justin Trudeau attacked the Conservatives as he unveiled a series of proposed reforms to Canada's government and democratic systems – but his real target were the progressive voters who are debating whether to support the NDP or his Liberal Party in the next election.

Under a Liberal government, Mr. Trudeau said Canadians would vote differently – either by using a preferential ballot or with proportional representation in the House of Commons – and get a different type of government. There would be more disclosure of government information, a cabinet with an equal number of men and women, unmuzzled scientists and more independence for MPs, as part of a package of 32 measures unveiled on Tuesday.

"[Prime Minister Stephen] Harper has turned Ottawa into a partisan swamp," Mr. Trudeau said, surrounded by Liberal MPs and candidates. "What we need is real change, and leadership that fixes what Stephen Harper has broken."

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The Liberal announcement came shortly before NDP Leader Thomas Mulcair strived to offer a reassuring economic message in a speech in Toronto, promising to personally promote Canadian manufacturers around the world if he becomes prime minister.

He added that provincial NDP governments have a strong record of balancing budgets, while acknowledging the record of Bob Rae in Ontario.

"There was one exception – but he turned out to be a Liberal," Mr. Mulcair said of the former premier who went into federal politics as a member of the Liberal Party of Canada.

Earlier in the day, the Angus Reid Institute released new poll numbers suggesting the NDP and the Liberal Party will spend the next four months fighting for the same votes.

An online Angus Reid survey of more than 6,005 Canadians found that among those who are likely to vote, 36 per cent support the NDP, 33 per cent support the Conservatives and 23 per cent support the Liberals. The polling firm noted that 23 per cent said the NDP would be their second choice, while 21 per cent would choose the Liberals. Conservatives are the second choice of just 7 per cent of decided likely voters.

"This will be quite the grudge match for that left-of-centre, anti-Harper, not-Harper vote," Angus Reid vice-president Shachi Kurl said in an interview.

Pollster Nik Nanos added that on this day, Mr. Mulcair and the NDP likely struck more of a chord with the voting public than the Liberal Party.

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"The thing voters think about is, 'What does this mean to me?' " he said in an interview. "When one leader stands up and talks about the economy, that means something to Canadians. When someone else talks about democracy and the rules of democracy, sadly that doesn't have the same type of impact."

Still, Mr. Nanos argued the Liberal message could also be aimed at disaffected Conservatives, such as populist supporters of the Reform Party who wanted a more decentralized Parliament.

"Stephen Harper rode into town promising to slay dragons," Mr. Trudeau said. "And 10 years later, he's walled up in his office cynically controlling his message and his caucus."

Another key demographic at play in the next election will be women voters. As he unveiled his policy for a "fair and open government," Mr. Trudeau said there would be the same number of female and male ministers in his cabinet.

Mr. Trudeau added the Oct. 19 general election would be the last one held under the "first-past-the-post" system, in which the candidate with the most votes is elected in his or her riding, regardless of the percentage of cast ballots that were obtained. The Liberal are promising to enact electoral reform within 18 months of forming a government, after launching a parliamentary study of proposals such as ranked ballots and proportional representation.

"We need to know that when we cast a ballot, it counts, that when we vote, it matters," Mr. Trudeau said.

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The Liberal proposal also includes major amendments to the Access to Information Act, in order to make data "open by default." The legislation would apply to the Prime Minister's Office and ministers' offices, which are currently shielded from the reach of the act.

Mr. Mulcair dismissed the Liberal promises, saying no one should trust Mr. Trudeau to enact major reforms.

"He hasn't stood for anything, now he stands for everything, including things [such as proportional representation] he voted against a couple of months ago," the NDP Leader said.