Obama will move into the Oval Office as leader of a country that is almost certainly in recession, and fighting two long wars, one in Iraq, the other in Afghanistan.

The popular vote was close — 51.3 percent to 47.5 percent with 73 percent of all U.S. precincts counted — but not the count in the Electoral College, where it mattered most.

There, Obama’s audacious decision to contest McCain in states that hadn’t gone Democratic in years paid rich dividends.

Obama has said his first order of presidential business will be to tackle the economy. He has also pledged to withdraw most U.S. combat troops from Iraq within 16 months.

A survey of voters leaving polling places on Tuesday showed the economy was by far the top Election Day issue. Six in 10 voters said so, and none of the other top issues — energy, Iraq, terrorism and health care — was picked by more than one in 10.

In Washington, the Democratic leaders of Congress celebrated.

“It is not a mandate for a party or ideology but a mandate for change,” said Senate Majority leader Harry Reid of Nevada.

Said Speaker Nancy Pelosi of California: “Tonight the American people have called for a new direction. They have called for change in America.”

Shortly after midnight in the East, The Associated Press count showed Obama with 338 electoral votes, well over the 270 needed for victory. McCain had 141 after winning states that comprised the normal Republican base.

Interviews with voters suggested that almost six in 10 women were backing Obama nationwide, while men leaned his way by a narrow margin. Just over half of whites supported McCain, giving him a slim advantage in a group that Bush carried overwhelmingly in 2004.