Men may enter politics for specious reasons, but they don’t remain for specious reasons. The stress is too great, the public too demanding. They only endure if their story rings true for themselves and their constituents.

I am a debate coach. My debaters plow through more than 10,000 evidence briefs in a year. They deliver at least 50 different arguments in an average debate round. They find evidentiary support for their arguments in policy journals, scientific studies, scholarly books, and daily newspapers. But, as I remind them, all their arguments and briefs matter only if, taken together, they support a coherent and persuasive story.

At the end of rounds, debate judges ask, “Which team had the better story?” Judges invariably award the round to the team that told the better story.

As voters in presidential elections, we also vote on story. Political analysts like to believe that we vote on single issues, cost-benefit analyses, or competing policy positions. All of those factor into our decision calculus. But a candidate can win most of the issues, but lose an election because his story does not resonate with voters.

As one ages, one invariably learns that a diet of journalism and nonfiction is deeply unsatisfying. The bare facts, shorn of personality, biography, and poetry, are a desiccated truth. They are not the whole of truth. For genuine truth to appear, there must be story.

As we look back on our life, and fit together the facts and fictions, the plans and visions, the loves and heartbreaks, we discover a story. A thread, perhaps invented, no doubt embellished, that gives us that precious, ineffable thing called meaning. This meaning is manmade. It has no enduring reality. But it gets us by. It helps us act. Without it, we are paralyzed, indifferent, very much empty and alone.

Because story is so integral to who we are as humans, it is also vital to almost every decision we make. When we consciously decide to buy a home, it’s because we’ve told ourselves a story about the purchase. This home fits somehow into the story we’ve been building in our minds: of how we will be in this particular home and this particular community. It’s the same with lovers, schools, jobs, and, yes, candidates.

A candidate’s job is, above all, to link his or her story with the stories of those he or she hopes to represent. This is not an easy feat. Many attempts in this regard are strained. Voters see through it. They reject politicos whose stories don’t match.

Mediocre politicians routinely get reelected because they have roots in their “home place” and because their story in its localized particulars matches the stories of their constituents. On the national scale, however, one cannot merely speak from personal experience. One must move from one’s highly particular experience to a general experience that rings true for millions of strangers.

In this year’s presidential election we have two competing narratives. They share a lot in common. Each is a journey of identity. Each is a journey of discovery. Each is a journey of service.

Most important, each has an air of urgency because each posits the nation at a crossroads, where we need to fundamentally change the way we do things. With McCain, we must put “Country First,” while remaining competitive globally. And in order to put Country First, we must punish those who have put Self before Country. For Mr. Obama, the theme is simple, but transcendent: for “America to be America again,” in Langston Hughes’ treasured words, Washington needs not reform, but radical surgery.

In the quiet of the voting booth, on the deepest level of choice, voters will decide between these conflicting stories. It won’t matter what they told the pollsters or what they told friends and family. What will matter is the story they told themselves.

Mr. Obama wants voters to believe that Mr. McCain’s story is merely a variation of the Bush story; not genuinely new, only pretend new. In the Obama critique, the courageous “maverick” has become a duplicitous hack, a robo-politician who deploys the politics of yesterday (including guilt-by-association, whisper campaigns, and all manner of ad hominem attacks), even as he promises to “shake up” Washington. By contrast, Mr. McCain wants voters to believe that a Senator from the disgraced Republican Party can actually be the change the country seeks, while his opponent represents merely the same old “tax-and-spend” softheaded liberalism with an appealing new face.

Unfortunately for Mr. McCain, as much as he has courageously bucked his party, he’s still the Republican candidate for president. Typically, for change to happen on the incumbent party’s terms, the incumbent party must first be ousted from power. The party would then go into the political wilderness to rediscover its soul, or at least a winning strategy.

From this very wilderness, Democrats birthed the successful moderate formula of Democratic Centrism that brought Bill Clinton to power from 1992-2000. When Republicans, in turn, journeyed into the political wilderness during the Clinton years, they came out believing that centrism would not serve them as well. So, in 2000, with G.W. Bush as their standard-bearer, they ran to their conservative base. Using incendiary ballot initiatives and sophisticated data mining, Karl Rove insured Bush victories by commandeering get-out-the base operations of unprecedented size and depth.

Sure enough, in 2000, after a disputed defeat, the Democrats went back into the wilderness. But only partially. In 2004, with Senator John Kerry, they ran a hybrid of Clintonian Centrism and old-line northeast liberalism. And they fared worse than they had in 2000, despite a failing war in Iraq and Bush’s growing unpopularity at home.

Come 2007, the presumptive nominee, Hillary Clinton, misread the political tealeaves. She figured the party wanted a full-throttle return to Democratic Centrism, but with that familiar Clinton imprimatur. It proved to be a superficial reading of the party’s mood.

Deep within the Democratic base another current was stirring. These diehard progressives never liked the compromises of Democratic Centrism: more cops on the street, a proactive use of U.S. military might, welfare reform, and a only tacit pursuit of green energy and environmental protection. They sat patiently on the sidelines during the Clinton years only to see Democratic Centrism fail them in both 2000 and 20004. Democratic Centrism was, to these diehards, merely a cult of personality surrounding a particular man at a particular time, not a consistently winning strategy in the face of hard-line GOP warfare.

Their answer was to elect a true progressive. Someone who was unequivocally anti-war, unabashedly in favor of federally mandated social programs, unequivocal about a woman’s right to choose, and a fearless advocate of green energy and environmental protection. But it was not enough that this candidate had the liberal bona fides (Mr. Obama was voted the most liberal member of the U.S. Senate by the National Journal). He also had to have enough charisma to win over independents and moderates, as Mr. Bush had so successfully done in two previous elections.

Most important, his story had to match a progressive agenda with the country’s past and future. As fate would have it, Mr. Obama’s mixed-parentage story was so authentic, so alive, so indubitably American, he couldn’t help but touch the hearts of millions, who saw in his odyssey their own. Barack Obama was both the embodiment of the final frontier in the long, tense history of American race relations, and a post-racial messenger of a new beginning. As his two biographies make clear, he had an oppressed minority’s knack of showing only the face the majority wanted to see. His true progressive agenda would be covertly alluded to only in symbolic tropes like “hope” and ”change,” not in overt and unnecessarily specific policy prescriptions.

We all know the John McCain narrative. It is one of personal courage, heroism, and adamantine survival. It’s a life built on taking big chances on behalf of big ideas in service of the commonweal.

Now that the debates are over, the Alfred Smith Dinner niceties out of the way, the crucial narrative questions emerge. First, who really is “the steady hand at the tiller”? Is it the tenacious, if “erratic,” P.O.W. with the experience of fighting wars, working across the aisles, and persisting against impossible odds, or is it the young, composed, meticulous, if slightly detached and camouflaged, constitutional lawyer?

Secondly, who are we as Americans? Are we exceptionalists, who, when the world turns against us, remain undaunted in the pursuit of our ideals? Or are we peacemaking multilateralists, who genuinely consult, and receive cooperation from, all parties before making a decision of world importance?

Finally, how big is the problem we face? Is it merely a question of reform, as Mr. McCain and Ms. Palin posit? Is it merely that the Republican Party veered away from its principles; and that all we need to do is to toss the bums out and begin a course correction back to those principles? Or is the disease so perniciously deep and persistent that it requires a wholesale rejection of the entire premise behind not only the G.O.P.’s governing philosophy but also the way both parties conduct politics itself?

Many of you readers may indeed believe that the last conclusion is the correct one. But, if so, you forget that this country is fundamentally conservative (or “center-right” in Patrick Buchanan’s oft-repeated words). First, a rejection of core Republican free market principles would indeed be a rejection of principles many Americans hold dear. Secondly, a rejection of “politics as usual,” i.e., a shift away from negative personal attacks, would not only suck the blood from a blood sport Americans secretly crave, but it would also unnecessarily sanitize a process many Americans believe tells them something elemental about the character, strength, and will power of the contenders. In other words, presumption rules heavy in the minds of voters until it is categorically proven that the presumed way of doing things has irrevocably failed.

This is why Mr. Obama is perceived to be risky. Not because he is personally disruptive, which he clearly is not, but because his carefully cloaked agenda might be. “Change” is a dirty word to people over 50. They don’t trust it, even if it’s in their interests. Which is why Mr. McCain has an easier task, even though the current economic climate dramatically favors his opponent. McCain merely has to show the will and experience to fight for the precise and necessary degree of change the current situation requires, and nothing more. By contrast, Mr. Obama must sell America on a voyage down unchartered waters.

He has already convinced voters that he’s a good and comforting captain, but many remain hesitant. As the last of the swing-state hold-outs stand on the shore that separates the safety of the known from the promise of the unknown, Mr. Obama must convince them that what sets them apart as Americans, is, in fact, a willingness to cross that threshold and become pilgrims anew. If there was a man, whose constitution and history were perfectly suited to tell such a story, it is surely Barack Obama.

Should he fail in selling this narrative, it would not be due to any fault in mind or mien, but, rather, to the equally compelling narrative proffered by his opponent in perfect lockstep with the deepest need of the American people: in times of great insecurity, to “cling,” in Mr. Obama’s treasured words, to what and whom they know.