WASHINGTON — For all the hue and cry in Canada about low voter turnout for October's federal election, one of the most momentous presidential votes in U.S. history didn't do a whole lot better.

Barack Obama swept to power last month amid predictions that record numbers of voters would emerge en masse to cast their ballots in favour of his message of hope and change.

But who really won him the election? According to a new voter turnout study, he owes much of his seven-point margin of victory over Republican John McCain not to a surge of voters, but to disgruntled conservatives who stayed home on election day.

About 130 million Americans voted on Nov. 4, up from 122 million four years ago but falling well short of the 140 million voters some experts had predicted.

That made for a 61 per cent voter turnout -- not much higher than Canada's much-maligned 59 per cent turnout for the Oct. 14 federal election, and still some distance away from the record-breaking 63.8 per cent in 1960, when John F. Kennedy beat Richard Nixon.

By contrast, Canadian voter turnout peaked at more than 79 per cent in 1958, when Conservative Prime Minister John Diefenbaker won what was, at the time, the largest majority government in Canada's history.

"We had the highest turnout here that we've had since 1964," Curtis Gans, the author of the election analysis conducted by American University's Center for the Study of the American Electorate, said Wednesday.

"But the number was lower than it could have been because some Republicans stayed home -- both the moderate Republicans who were appalled by the choice of Sarah Palin as the vice-presidential nominee, and by what McCain did when he suspended his campaign during the economic crisis, and the very conservative Republicans who didn't like McCain because they viewed him as too centrist."

Gans also cited a sense of resignation among conservatives in the face of an Obama juggernaut.

"There was a defeatist attitude at play, and in addition to the fact that both sides of the Republican party had some disaffection for the ticket, that influenced the level of turnout and likely influenced the margin."

And while millions of newly registered black voters did indeed show up to cast ballots for Obama, their numbers were offset by a lower number of youth voters than expected, meaning the conservatives who stayed home proved significant.

Most of those who identify themselves as Republicans did show up on Nov. 4, but Gans said a significant number voted for Obama, who picked up a third more conservative voters than John Kerry did in 2004. That was enough to help win him the election.

It all spells trouble for the Republicans, said Gans, noting the significant inroads made by the Democrats in traditionally conservative territory in the U.S. south.

"All of this could be temporary, but it doesn't seem that a lot of the Republicans who voted Democrat this time are going to go back to a socially conservative party," he said.

"America is changing and the Republican party is going to have to change along with it."

David Frum, the Canadian-born pundit who's become one of the most respected voices of the right in the U.S., agreed that the party is at a crossroads.

"It's not being discussed yet within the party for the very natural reason that parties are big conservative institutions that take a while to change, and the consensus about how you reorient yourself can take a lot of time," he said.

"In the past, it's often taken several years and more than one election cycle for a party to reinvent itself. Things move faster now due to the Internet and the 24-hour news cycle, however, so I am hopeful we will have some positive evolution."