State election officials submitted a final tally on Dec. 31 that added about 400,000 votes, most of them from provisional ballots in the Democratic stronghold of New York City that were counted late in part because of complications caused by Hurricane Sandy.
Nationally, Obama won 65.9 million votes, or 51.1 percent, against Republican challenger Mitt Romney, who took 60.9 million votes and 47.2 percent of the total cast, according to data compiled by Bloomberg.
Obama is the first president to achieve the 51 percent mark in two elections since Republican Dwight D. Eisenhower, who did it in 1952 and 1956, and the first Democrat to do so since Franklin D. Roosevelt, who won four consecutive White House races. Roosevelt received 53.4 percent of the vote — his lowest — in his last race in 1944.
Obama, 51, benefited from political factors that included a lack of serious opposition for his party's nomination or from well-known third-party challengers, and an absence of social unrest, scandal or foreign-policy disasters during his first term, said Allan Lichtman, a history professor at American University in Washington.
"Under the big picture, this was an entirely predictable election outcome," Lichtman said.
The president won the popular vote in 26 states and the District of Columbia, totaling 332 electoral votes, or 62 more than the 270 needed to win the presidency. Romney won 24 states with 206 electoral votes. Obama won 365 electoral votes in 2008.
Congress certified the 2012 electoral votes in a joint session today. Obama will take the oath of office on Jan. 20, a Sunday, and give his inaugural speech at the Capitol on Jan. 21.
Turnout in this year's presidential race was about 129.1 million, down from the record 131.3 million four years ago.
Obama's national vote total fell by about 3.6 million votes from his record 69.5 million in 2008, when he was elected the nation's first black president. In that race, he won 52.9 percent — with a victory margin of more than 9.5 million votes over Republican John McCain — amid a financial crisis that took hold at the end of Republican George W. Bush's presidency.
The nation's unemployment rate, 7.8 percent when Obama succeeded Bush in January 2009, rose to 10 percent that October before falling to 7.7 percent last November. Obama is the second president since World War II to win re-election with a jobless rate above 6 percent. The other was Republican Ronald Reagan in 1984.
"He was able to campaign against the economy back in 2008 because it was Bush's problem," Rhodes Cook, a political analyst who publishes a newsletter, said in an interview. "It got reversed. He got stuck with the economy this time."
Romney, a former private-equity executive and governor of Massachusetts, failed to parlay voter anxiety about the economy into a victory.
While Obama's national vote percentage fell by about 2 points from four years ago, he improved on his 2008 performance in six states, including New York, where his 63.3 percent was the best by any presidential nominee since 1964, and New Jersey, where his 58.3 percent was the best by a Democratic White House hopeful since 1964.
In just four states — Florida, North Carolina, Ohio and Virginia — was the winning candidate's margin of victory less than 5 percentage points, the smallest number of states below that threshold since 1984, when three states were within 5 points amid Reagan's 18-point victory in the popular vote over Democrat Walter Mondale.
In 2004, when Bush was re-elected with a popular vote margin of less than 3 points over Democrat John Kerry, 11 states were decided by fewer than 5 points. In 1976, when Democrat Jimmy Carter won the White House and edged President Gerald Ford by 2 points, 20 states were within 5 points.
The Nov. 6 results underscore challenges for Republicans as they seek an Electoral College majority in 2016 and beyond.
Eighteen states and the District of Columbia, with a total of 242 electoral votes, have voted Democratic in six straight presidential elections. They include the biggest electoral-vote prize, California, where Obama won its 55 electoral votes with a 23-point win.
Twenty-two states with 180 electoral votes have voted Republican in the past four elections.
"You have an electorate that's very polarized and pretty even, though it's a situation now though where the Democrats seem to have a little better handle on the map than the Republicans do," Cook said.
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