Underestimated throughout his political career, Liberal leader Stephane Dion is hoping for another upset in Canada's general election, with his party closing in on the incumbent.

From the outset, Mr Dion characterised by his Conservative rival as a weak leader has struggled to improve his popularity.

His party's main election plank for the largest tax shift in recent Canadian history, slashing income and corporate taxes to offset a new pollution tax, has been a hard sell to voters fearful of big changes during a period of economic uncertainty.

But with stockmarkets tumbling, and a prediction last week that Canada will fall into recession next year, Conservative Prime Minister Stephen Harper's ''stay the course'' campaign has stumbled.

Suddenly, Mr Dion was cast in a new light, touting the Liberals' record of responsible economic stewardship balanced with concern for those most in need of social programs.

He declared himself prepared to take urgent steps to stem the financial crisis while accusing Mr Harper of glossing over Canadians' economic fears.

In recent days, polls have shown the Liberals bridging the gap with the Conservatives, and for a brief time running neck and neck as they head for the finish line overnight on Wednesday Canberra time.

But with five main parties in the race, pundits point out there are no sure bets, and Mr Dion is gambling his political career on the outcome.

A lanky former professor who celebrated his 53rd birthday on the campaign trail, Mr Dion has already proved he can come from behind to win.

In December 2006, he surprised everyone by beating the front-runners for the leadership of the Liberal Party, which had been relegated to the Opposition benches in the general election at the start of the same year.

Mr Dion's lack of charisma and his difficulties expressing himself in English the language spoken by three-quarters of Canadians have often eclipsed his integrity and intellectual prowess.

The son of a renowned Quebec academic, Mr Dion also taught at university before being elected to the House of Commons in 1996, only a few months after the failed 1995 referendum on Quebec sovereignty.

The next year, then prime minister Jean Chretien appointed Mr Dion intergovernmental affairs minister, to fight for Canadian federalism.

Mr Dion unveiled the Clarity Act, setting out new, tougher benchmarks for a province to split from the rest of Canada, angering Quebec nationalists. That law haunts him still in this campaign. AFP