Between 60.7 percent and 61.7 percent of the 208.3 million eligible voters cast ballots this year, compared with 60.6 percent of those eligible in 2004, according to a voting analysis by American University political scientist Curtis Gans, an authority on voter turnout.

He estimated that between 126.5 million and 128.5 million eligible voters cast ballots this year, versus 122.3 million four years ago. Gans said the gross number of ballots cast in 2008 was the highest ever, even though the percentage was not substantially different from 2004, because there were about 6.5 million more people registered to vote this time around.

The Democratic increase struck some analysts as modest, considering the party’s immense get-out-the-vote operation, strong anti-Bush sentiment and Obama's popularity.

“It sort of calls into question some of the vaunted ground game discussion, the whole turnout machine,” said a Democratic strategist who did not want to be quoted by name criticizing Obama’s campaign. “The GOTV effort was redoubled in 2008 compared to 2004, but it did not seem to make that big of a difference.”