WASHINGTON (AP) — Barack Obama swept to victory as the nation’s first black president Tuesday night in an electoral college landslide that overcame racial barriers as old as America itself. “Change has come,” he told to a huge throng of jubilant supporters.

The son of a black father from Kenya and a white mother from Kansas, the Democratic senator from Illinois sealed his historic triumph by defeating Republican Sen. John McCain in a string of wins in hard-fought battleground states — Ohio, Florida, Virginia, Iowa and more.

On a night for Democrats to savor, they not only elected Obama the nation’s 44th president but padded their majorities in the House and Senate, and come January will control both the White House and Congress for the first time since 1994.

Obama’s election capped a meteoric rise — from mere state senator to president-elect in four years.

In his first speech as victor, to thousands at Grant Park in his home town of Chicago, Obama catalogued the challenges ahead. “The greatest of a lifetime,” he said, “two wars, a planet in peril, the worst financial crisis in a century.”

He added, “There are many who won’t agree with every decision or policy I make as president, and we know that government can’t solve every problem. But I will always be honest with you about the challenges we face.”

President Bush added his congratulations from the White House, where his tenure runs out on Jan. 20.

Obama, in his speech, invoked the words of Lincoln and echoed John F. Kennedy.

“So let us summon a new spirit of patriotism, of service and responsibility where each of us resolves to pitch in and work harder,” he said.

His victory speech was delivered before a multiracial crowd of more than 100,000 people. Many cried and nodded their heads while he spoke, surrounded by clear bulletproof screens on his left and right.

“If there is anyone out there who still doubts that America is a place where all things are possible; who still wonders if the dream of our founders is alive in our time; who still questions the power of our democracy, tonight is your answer,” he said in his first public words after winning the election.

He appeared on stage with his wife, Michelle, and daughters Malia, 10, and Sasha, 7, set to become the first family of color ever to occupy the White House. Every family member dressed in black and red.

To those who voted against him, he said, “I will be your president, too.”

“Even as we celebrate tonight, we know the challenges that tomorrow will bring are the greatest of our lifetime — two wars, a planet in peril, the worst financial crisis in a century,” he said. “There is new energy to harness and new jobs to be created; new schools to build and threats to meet and, for us to lead, alliances to repair.”

He and his running mate, Sen. Joseph Biden of Delaware, will take their oaths of office as president and vice president on Jan. 20, 2009.

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.