By David Ljunggren
OTTAWA/TORONTO (Reuters) - Canadians vote on Monday in one of their most unpredictable elections ever, one that could just as easily hand the ruling Conservatives a solid grip on power or leave them so weak they could soon lose office.
The right-of-centre Conservatives, who have governed Canada since early 2006, started the campaign with a healthy lead and said they needed a majority of seats in the House of Commons to let them focus on the economic recovery and keep taxes low.
Over the last two weeks, Prime Minister Stephen Harper has watched his advantage dwindle in the face of an extraordinarily effective campaign by the left-leaning New Democrats, a pro-labour party that has never held power in Canada.
"NDP biggest surprise of campaign," Canada's Globe and Mail newspaper said in its lead election story on Monday that questioned whether the Harper government could secure a majority government.
An editorial in the National Post newspaper urged Canadians to "Get out and vote," underscoring the fact that turnout will be especially key for the party that draws so much support among young people who sometimes do not make it to the polls.
Casting all caution aside on Sunday, the last day of campaigning ahead of the parliamentary election, New Democrat leader Jack Layton predicted victory for the first time.
"I want you to create line-ups at the polls, my friends, because we can defeat Stephen Harper," he told a rally.
The New Democrats promise to increase corporate taxes, limit the amount of interest banks can impose on credit card balances and introduce a cap and trade system to curb the greenhouse gases blamed for global warming.
Harper says the result would be economic disaster at a tine when Canada -- the largest single supplier of energy to the United States -- is recovering nicely from the global crisis.
"A New Democrat government means higher prices, smaller pay checks, a weaker economy," he told a rally on Sunday.
Harper won minorities in 2006 and 2008, which obliged him to cooperate with opposition parties to pass budgets and other major legislation. The Conservatives currently hold 143 of the 308 seats in the House of Commons.
The combative prime minister says if he gets another minority the New Democrats and Liberals will quickly unite to oust him and create what he calls a dangerous coalition.
A three-day rolling poll by Nanos Research late on Sunday put public support for the Conservatives at 37.1 percent with the New Democrats at 31.6 percent. The Liberals, who started the campaign in second place, were at 22.5 percent.
The New Democrats and the Liberals are competing for the same centre-left voters and if they split the vote, the Nanos poll shows the result could mean a narrow majority for Harper. That would ensure him a fixed four-year term in power.
An Ekos poll, also released late on Sunday, said the result would be much closer. It had the Conservatives at 33.9 percent, the New Democrats at 31.2 percent and the Liberals at 21.0 percent. No opinion polls are allowed on election day.
(Additional reporting by Pav Jordan; Editing by Cynthia Osterman)
