In a sign these changes are more glacial than seismic, Obama, who announced his support for gay marriage in May, lost North Carolina, where voters there overwhelmingly voted against allowing gay marriage the same month.
There also were signs divisions between opponents had deepened.
Voters were more ideologically polarized than in 2008 or 2004. The share of moderates dipped slightly to 41 percent, while 25 percent called themselves liberal, the highest share saying so in recent surveys of voters as they leave their polling places. Thirty-five percent called themselves conservative, about the same as the previous two presidential contests.
The 2012 electorate mirrored 2008 in terms of party identification and racial makeup, with self-identified Democrats topping Republicans and independents.
During his victory speech, Obama nodded to the Democratic coalition he had held together.
"It doesn't matter if you're black or white, or Hispanic or Asian, or Native American, or young or old or rich or poor, able, disabled, gay or straight," Obama told his crowd of supporters gathered in Chicago. "You can make it here in America if you're willing to try."
Assumptions by Romney about the minority and youth turnout weren't the only ones that turned out to be wrong.
While voters considered the economy the driving issue in the election, they did not hold Obama wholly responsible, as Romney long had assumed they would.
That realization forced Romney to pivot late in the campaign and attempt to turn the election into a choice of competing visions. Republicans argued late in the campaign that Romney's performance during the first of three debates had energized a groundswell of enthusiasm seen in their polling.
But it seemed Obama's support was quietly amassing with more vigor, GOP strategists said.
"There really wasn't an enthusiasm gap," said Republican strategist Charlie Black, an informal Romney adviser. "And independents didn't break our way."
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