A historic victory. A changed nation. Now, can Obama deliver?

It was a night Americans said, "Enough!"

They crashed the polls to cast ballots for Barack Obama. But they also cast their vote against the politics of fear. Against trickle-down economics that don't trickle. Against wars with no end in sight. Against President Bush and his party.

Mr. Obama's victory was historic: America's first African-American president, and arguably the first black leader of any white-majority nation in recorded history. And he led the Democratic Party to one of its best nights in half a century.

But the Democrats' jubilation, their celebration, will be short-lived. Because from January, they'll have to shoulder all the blame.

Still, this is a moment for them to savor. The political landscape has been transformed – by the soaring rhetoric of change, superb organization, and a groundswell of grass-roots activism.

Obama's victory was powered by a surge of voters under 30, the passion of African-Americans who stood in long lines in key early-voting states, and surprisingly strong support among Hispanics.

But exit polls show he also won nearly 1 in 5 of Bush's 2004 supporters. And 41 percent of white men. That may not seem like much, until you consider that no Democrat since Jimmy Carter had until Tuesday's election earned more than 38 percent of the white male vote. Obama also became the first Democratic presidential candidate since Carter to win a majority – not just a plurality – of votes.

It is Obama's very appeal across divides of age, race, and ideology that led Colin Powell to declare that Obama could prove to be a "transformational figure."

"We are watching history," said Roger House, an Emerson College historian.

Still, if Obama's victory is an indelible marker of the country's progress on race, the staying power of his presidency and party will depend on his performance from his first day in office.

Political scientists talk about "realignment" – rare pivot points in American history when the public adopts a fundamentally different political outlook. The 1932 election was one, the Reagan Revolution of 1980 was another. Could 2008 be, too?

Possibly. Cautions Thomas Patterson, a professor of government at Harvard's Kennedy School: "He's got to deliver and I think he's got to deliver in some really big ways."

"Is this going to be transformational?" Mr. Patterson continues. "I think that fundamentally gets down to, 'Is anything going to happen?' It's not just the election. It is the presidency that is going to give us the answer."

Patterson recalls Carter's presidency, which began in the aftermath of Watergate and Vietnam with the promise of greater trust in government. It lasted just four years, a victim, among other things, of stagflation, an oil crisis, and a standoff with Iran. Sound familiar?

"If anything, conditions out there now are worse," he says.

Sobering. And yet Obama will begin his presidency with a level of global support unrivalled since perhaps John F. Kennedy. A Gallup poll taken in 73 countries earlier this year found his support topped John McCain's by greater than 3 to 1. His personal history – his childhood years in Indonesia, his search for his African roots – makes him uniquely suited to spread America's message abroad. And his call for diplomacy before intervention stand in stark contrast to the combative unilateralism of the Bush years and offer an opportunity to lift America's sagging standing in the world.

His campaign has mobilized citizens in fresh and original ways. His fundraising – much reliant on millions of small donors – shattered records. His get-out-the-vote campaign precipitated the highest level of early voters ever. His reach extended to all regions of the country. And though it's not official yet, evidence suggests overall voter turnout was the best in generations.

Obama's presidency will depend on many factors outside his control. But it will also depend on the tone he sets. On that score, he already has built a foundation of reaching out to the other side – a side that suddenly feels itself diminished. As Obama has repeatedly said, it's not about red states or blue states but about the United States of America.

"If he can change the political culture of this country, then he's changing the world for his children," says Michael Brown, another Emerson colleague.

In his victory speech, Obama began to launch that change with a call for service and sacrifice to help others in these hard economic times. Perhaps a new Civilian Volunteer Corps could provide such assistance, and serve as an immediate symbol of Obama's call for governance that bubbles up rather than being handed down.

For a quarter century, Americans have heard that government is the problem, not the solution. Obama has yet to turn that perception, yet to crystallize that solution. But he has set a tone that improves his odds of doing both. He has also shown his toughness.

When Obama began his quest for the presidency almost two years ago, he faced nearly insurmountable hurdles, starting with the legendary Clinton machine. He cleared every one. Throughout the campaign, he withstood a barrage of labels – Marxist, Muslim, pal of terrorists – and emerged stronger, more determined, undeterred in his calls for unity.

An even greater test, however, lies squarely ahead: converting the call for change to reality in very shaky economic times.

• Jerry Lanson teaches journalism at Boston's Emerson College.