As the real campaign at last began in Denver last week, this much is certain: It's time for Barack Obama to dispatch "Change We Can Believe In" to a dignified death.

This isn't because – OMG! – Mr. Obama's narrow 3- to 4-point lead of recent weeks dropped to a statistically indistinguishable 1- to 3-point margin during his week of vacation. It's because zero hour is here. As the presidential race finally gains the country's full attention, the strategy that vanquished Hillary Clinton must be rebooted to take out John McCain.

What we have learned this summer is this: Mr. McCain's trigger-happy temperament and reactionary policies offer worse than no change. He is an unstable bridge back not just to Bush policies but to an increasingly distant 20th-century America that is still fighting Red China in Vietnam and the Soviet Union in the Cold War. As the country tries to navigate the fast-moving changes of the 21st century, Mr. McCain would put America on hold.

What Mr. Obama also should have learned by now is that the press is not his friend. Of course, he gets more ink and airtime than Mr. McCain; he's sexier news. But as George Mason University's Center for Media and Public Affairs documented in its study of six weeks of TV news reports this summer, Mr. Obama's coverage was 28 percent positive, 72 percent negative. (For Mr. McCain, the split was 43-57.)

What should Mr. Obama do now? He needs to sell policy with an effective story – but it has to be a story that is more about America and the future and less about Mr. Obama and his past. After all these months, most Americans, for better or worse, know who Mr. Obama is. So much so that he seems to have fought off the relentless right-wing onslaught to demonize him as an elitist alien.

Asked in last week's New York Times/CBS News poll if each candidate shares their values, registered voters gave Mr. Obama and Mr. McCain an identical 63 percent. Is the candidate "someone you can relate to"? Mr. Obama: 55 percent, Mr. McCain: 41. Even before Mr. McCain told Politico that he relies on the help to count up the houses he owns, he was the candidate seen as the out-of-step elitist.

Economic anxiety is the new terrorism. This is why the most relevant snapshot of voters' concerns was not to be found at Saddleback Church but at the Olympics. This was a rare feel-good moment for a depressed country.

But the unsettling subtext of the Olympics has been as resonant for Americans as Michael Phelps' triumph. You couldn't watch NBC's coverage without feeling bombarded by an ascendant China whose superior cache of gold medals and dazzling management of the Games became a proxy for its spectacular commercial and cultural prowess in the new century. Americans watching the Olympics could not escape the reality that China in particular and Asia in general will continue to outpace our country in growth while we remain mired in stagnancy and debt.

How we dig out of this quagmire is the American story that Mr. Obama must tell. It is not a story of endless conflicts abroad but a potentially inspiring tale of serious economic, educational, energy and health care mobilization at home. We don't have the time or resources to go off on more quixotic military missions or to indulge in culture wars.

Americans must band together for change before the new century leaves us completely behind. The Obama campaign actually has plans to set us on that path; the McCain campaign offers only disposable Band-Aids.

Even as it points to America's future, the Obama campaign also has the duty to fill in its opponent's past. Mr. McCain's attacks on Mr. Obama have worked: In a recent Los Angeles Times-Bloomberg poll, Mr. Obama's favorable rating declined from 59 to 48 percent and his negative rating rose from 27 to 35. Yet Mr. McCain still has a lower positive rating (46 percent) and higher negative rating (38) than Mr. Obama. Should voters actually get to know him, he has nowhere to go but down.

The argument against Mr. Obama's "going negative" is that it undermines his message of "transcendent politics" and will make him look like an "angry black man." But pacifistic politics is an oxymoron, and Mr. Obama is constitutionally incapable of coming off angrier than Mr. McCain.

Is a man who is just discovering the Internet qualified to lead a restoration of America's economic and educational infrastructures? Does a bellicose Vietnam veteran who rushed to hitch his star to the self-immolating overreaches of Ahmad Chalabi, Pervez Musharraf and Mikheil Saakashvili have the judgment to keep America safe?

R.I.P., "Change We Can Believe In." The fierce urgency of the 21st century demands Change Before It's Too Late.

Frank Rich is a New York Times columnist.