With each passing day, it seems more certain that Barack Obama will do what was once unthinkable. As his deficits in Ohio and Texas polls shrivel to preclude the possibility of catastrophic defeats that would put the race back into play, Mr. Obama will almost assuredly defeat the most powerful and gifted Democratic family in existence to win the nomination of the party, which they singlehandedly lent relevance to for some time.

And when the dust settles around a sealed Obama nomination after the March 4 primaries, the hard part will begin.

It will not be a cakewalk to the White House. John McCain is a highly respected candidate, and his name on the ballot will give Americans of diverse backgrounds and ideologies pause come election time, if nothing else. To defeat Mr. McCain, the Obama camp faces an entirely new set of challenges.

One of these challenges is for Mr. Obama to continue to meet the astronomical expectations he has set for himself as a candidate and human being. As conservative columnist William Kristol noted in The New York Times this week, though Mr. Obama?s rhetoric seeks to empower supporters by suggesting he is a symbol of their own desire to work toward a conciliatory political climate, his candidacy?s implied raison d?etre is that he is a singular force of change the likes of which Americans will not see again.

?Obamania? is only made possible by the man?s unique combination of qualities: proven intellect, multinational ethnic heritage, non-contradictory political record, traditional family life, unimpeachable ethics and just enough experience in federal government to demonstrate competency while still allowing him to refer to Washington as ?the other.? Take away one of these, and he might cease to be such a source of inspiration.

So, if we were to see less-than-beatific behavior from Mr. Obama in the long second leg to the presidency, whether in the form of unearthed political inconsistencies or skeletons from his personal history?s closet, would he continue to dominate? If a certain flaw is revealed that makes Mr. Obama seem incapable of being a ?uniter,? or even simply less than perfect, will his campaign lose steam? Mr. Obama?s approach demands perfection, and it is one that can be both enormously successful and extremely volatile.

It also remains to be seen whether Mr. Obama can capitalize on the bipartisan support surrounding his campaign as we enter the more polarized general election stage.

American presidential campaigns are personality-focused, and never more so than in pre-nomination. Character traits are decisive in early votes because party compatriots tend to run on very similar platforms. Democratic debates this season have been a perfect example ? on every major issue it seemed as if there was an echo in the room. Candidates are really only composed of two variables ? policy and persona ? and when distinctions in the former are close to nil, selections are based on the latter.

Thus, it has been Mr. Obama?s immense capacity to inspire, not the particulars of his policies, that has been instrumental in carrying him to the brink of first-round victory.

But I?m afraid this curiosity will become extinct in the harsher environs of the general election. Unlike intra-party contests, McCain-Obama will not only offer voters two unique personalities and biographies, it will present two drastically different policy platters.

Contrary to the Clintons? contention, Mr. Obama?s campaign is proposing many bold, substantive changes. Perhaps complicating dreams of bipartisan unity, many of these ? including making the social security tax code more progressive, cutting corporate tax loopholes and slowing the pace of trade liberalization ? are at odds with economic policies traditionally favored by Republicans.

In a recent poll by Rasmussen Reports, a whopping 80 percent of voters indicated the economy is ?of top importance as an electoral issue.? In light of this, bipartisan support for Mr. Obama has the potential to dry up when Republicans come face-to-face with his economic prescriptions. Can an Obama candidacy survive votes inevitably determined by individuals? pocketbooks? Will there be any surviving Obamacans come November?

Though politics would be a secondary concern in such an event, a national security crisis would likely rally public support behind a longtime military man such as Mr. McCain. It wouldn?t even necessarily take a terrorist attack on the homeland ? any signs of global unrest perceived as threatening to American interests could radically change the race.

A reawakening of Chinese military aggression toward Taiwan, bold moves by Iran, continued Russian intransigence on nuclear issues, even a critical mass of African upheavals ? any of these could sink Mr. Obama, who has not convinced many Americans that he could serve as a strong commander in chief in a crisis. Besides the continued violence in Iraq, we have been lucky to live in relative peace for the last few years. Does the Obama camp have a contingency plan for more trying times?

The Obama campaign has, and can continue to be, a great national antidote to Bush-era polarization. But after March 4, the game changes completely. Here?s hoping Mr. Obama can adjust to the trials that lie ahead.

John Sprangers ([email protected]) is a senior majoring in political science and international studies.