TORONTO - When the lights went out one hot August afternoon five years ago, then-premier Ernie Eves - like most people in Ontario - didn't think much of it.

Brief power outages were a common occurrence at his home in Caledon, about 40 kilometres northwest of Toronto, where Eves was preparing for a nomination meeting that would have signalled that an election was imminent.

"So when power went out, I just assumed it was a simple case of 'Oh well, here we go again,"' he said.

"That turned out, obviously, not to be true. And we had a much more serious problem."

Within minutes, Eves was transported to the local provincial police station, then flown to Toronto by helicopter, which landed in a downtown schoolyard. The city, along with much of Ontario and eight U.S. states, had been plunged in complete disarray.

Streetcars and subways had halted in their tracks, trapping commuters in pitch-black tunnels below streets gridlocked with rush-hour traffic. Seniors were stuck in elevators and high-rise apartments, while stranded airport passengers anxiously wondered if the country was under terrorist attack.

What had initially been dismissed as a temporary blip in the power grid on Aug. 14, 2003 turned out to be the largest blackout in North American history, leaving some 50 million people without electricity, including major cities like New York.

Eves recalled his cabinet and declared a state of emergency, launching a massive conservation effort that lasted more than a week while the power grid recharged.

"I know I virtually lived at command headquarters for many days," he recalls.

"And it was very rewarding to see how people pulled together. I mean, people didn't point fingers or blame, they just got on with solving the problem."

But there was a political price to be paid. Three months after the power went out, voters pulled the plug on his Conservative government, ending the party's eight-year reign in Ontario.

The blackout was a dramatic symbol of the "indecision and dithering" that plagued Eves' government, which was still recovering from the SARS outbreak in Toronto and lingering worries over mad cow disease, said Bryan Evans, associate politics professor at Toronto's Ryerson University.

"The blackout brought everything together around the kind of indecision that was beginning to form about the Eves government," he said.

Criticized for being slow to respond in the first hours of the blackout, Eves became a media fixture as the outage dragged on, providing regular updates on the situation while urging businesses and residents to conserve power.

His approval ratings shot up in the wake of the crisis, but it wasn't enough to dislodge the growing public perception that the Conservatives were doing a poor job of running the province, said Henry Jacek, a political science professor at Hamilton's McMaster University.

Eves's ill-fated decision to unveil the 2003 budget from the headquarters of auto parts giant Magna International - a public relations disaster that members of his own party publicly condemned - planted the seeds of doubt that would later flourish in the weeks following the blackout, said Jacek.

"I think the decline and the image was already there, and this was just another piece of evidence for the public - at least they interpreted it that way - that he was not a good public manager," he said.

The blackout began when a transmission line in Ohio failed, causing a domino effect that resulted in power outages in Ohio, Michigan, Pennsylvania, New York, Vermont, Massachusetts, Connecticut, New Jersey and Ontario. It took four days for power to be restored in the U.S., while brownouts and rolling blackouts continued for more than a week in Ontario.

Looking back, Eves said he doesn't believe the blackout alone cost his party the 2003 election, which ushered in two back-to-back Liberal majority governments for the first time in 70 years.

"Well, if I knew the answer to all those questions, I might still be there," Eves said, chuckling. "Quite seriously, it's hard to say. I mean, I don't think you can take one specific thing."

In the end, it was a "culmination" of events that caused the Tories to lose the election and their hold on the province - the most important of which was the public's desire for a change in government, Eves added.

Since then, the governing Liberals have worked to fix weaknesses in the system that had been exposed by the blackout, said Energy and Infrastructure Minister George Smitherman, who took over the portfolio in June.

Hydro One is involved in a $1.5-billion plan which includes reinforcing the existing transmission system, he said. The province is also investing heavily in new power generation, such as wind farms and gas-fired plants, while undertaking a $26.3-billion plan to refurbish and replace its aging nuclear fleet, Smitherman said.

"I don't think that you can possibly rule out every eventuality, but I think all of the objective analysis points to the province of Ontario being involved in a pretty substantial renaissance of its electricity system," he said.

But a massive power failure on the scale of the 2003 blackout could happen again, warned NDP Leader Howard Hampton.

Energy demand has waned since 2003 because Ontario's economy is no longer booming and factories are shutting down, he said. Meanwhile, the province is stuck with a transmission system that's still "very vulnerable" to shocks south of the border.

"If you had a major transmission failure in the United States, it would ricochet into Ontario," Hampton said.

"As it is, there isn't enough transmission right now to carry some of the proposed electricity to where it's needed. So is it likely to be imminent? No. Could it happen again? Sure could."

The blackout also highlighted the need for more long-term planning by governments, a lesson the Liberals have failed to learn, said Progressive Conservative Leader John Tory.

"Not only is (Premier Dalton) McGuinty's government not prepared for the unexpected, they're not even preparing for the expected, which is a shortage of energy going forward," he said.

"They're just not making the plans and making them fast enough to deal with the energy situation in years to come."