Conservative Stephen Harper, Liberal Michael Ignatieff and Jack Layton of the New Democratic Party
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Canadian election campaign sees NDP gaining fast

Canada is facing a potential political shake-up when polls open on Monday for the third election in five years, as a once marginal party threatens to upset the status quo.

Conservative leader Stephen Harper is hoping his party gains enough votes to promote his two-term minority government to majority rule.

But while polls had shown them to be ahead of their traditional rivals - Michael Ignatieff's Liberals - support for the New Democratic Party, lead by Jack Layton, is growing fast.

Andrew North reports from Toronto.