Challenges facing Barack Obama: 10-point cheat-sheet

Obama's win is not likely to change the dynamic in Washington. Obama's victory will not strike fear into the hearts of Republicans, who are projected to retain control of the House of Representatives. Obama's Democrats will hold on to the Senate, but fewer moderates of either party will be returning to Capitol Hill.

That is a recipe for more white-knuckle showdowns over taxes and spending, and gridlock in other areas. Reaching consensus on even the most routine legislation will be difficult.

"If there's no perception that going against Obama would detrimentally affect Republicans in 2016, there's not going to be a lot of goodwill on the Hill," said Princeton University history professor Julian Zelizer. "The party lines will be hardened after this election."

The economy showed just enough of a pulse to return Obama to office. The United States is still digging out from the deepest recession in 80 years, and employers are barely adding enough jobs to keep up with population growth. But if the economy is not exactly roaring ahead, it improved steadily over the course of the year.

Historically, voters have given a second term to presidents who preside over even modest economic growth during an election year. That pattern appears to have held for Obama.

"It was never going to be a landslide," said John Sides, a political science professor at George Washington University. "But it was always his race to lose."

Obama also was helped by the fact that voters largely blame the recession on his Republican predecessor, President George W. Bush, and Obama argued that Romney would bring back policies that led to the crash in the first place.

The auto bailout provided a crucial boost in Ohio.Obama scored many legislative victories in his first two years in office, but they have not been terribly popular with the public.

But Obama's 2009 bailout of General Motors and Chrysler has been popular with a crucial slice of the electorate: white men in Ohio, where roughly 1 in 8 jobs is tied to the auto industry.

Obama did not win the white-male vote in Ohio, but he did better with that group in Ohio than elsewhere. According to Reuters/Ipsos exit polls, Obama lost white men nationwide by 20 percentage points. In Ohio, he lost by only 13 percentage points.