The choice is made easy in part by Mr. McCain's disappointing campaign, above all his irresponsible selection of a running mate who is not ready to be president. It is made easy in larger part, though, because of our admiration for Mr. Obama and the impressive qualities he has shown during this long race. Yes, we have reservations and concerns, almost inevitably, given Mr. Obama's relatively brief experience in national politics. But we also have enormous hopes.

Mr. Obama is a man of supple intelligence, with a nuanced grasp of complex issues and evident skill at conciliation and consensus-building. At home, we believe, he would respond to the economic crisis with a healthy respect for markets tempered by justified dismay over rising inequality and an understanding of the need for focused regulation. Abroad, the best evidence suggests that he would seek to maintain U.S. leadership and engagement, continue the fight against terrorists, and wage vigorous diplomacy on behalf of U.S. values and interests. Mr. Obama has the potential to become a great president. Given the enormous problems he would confront from his first day in office, and the damage wrought over the past eight years, we would settle for very good.

The first question, in fact, might be why either man wants the job. Start with two ongoing wars, both far from being won; an unstable, nuclear-armed Pakistan; a resurgent Russia menacing its neighbors; a terrorist-supporting Iran racing toward nuclear status; a roiling Middle East; a rising China seeking its place in the world. Stir in the threat of nuclear or biological terrorism, the burdens of global poverty and disease, and accelerating climate change. Domestically, wages have stagnated while public education is failing a generation of urban, mostly minority children. Now add the possibility of the deepest economic trough since the Great Depression.

Not even his fiercest critics would blame President Bush for all of these problems, and we are far from being his fiercest critic. But for the past eight years, his administration, while pursuing some worthy policies (accountability in education, homeland security, the promotion of freedom abroad), has also championed some stunningly wrongheaded ones (fiscal recklessness, torture, utter disregard for the planet's ecological health) and has acted too often with incompetence, arrogance or both. A McCain presidency would not equal four more years, but outside of his inner circle, Mr. McCain would draw on many of the same policymakers who have brought us to our current state. We believe they have richly earned, and might even benefit from, some years in the political wilderness.

Mr. Obama offers a great deal more than being not a Republican. There are two sets of issues that matter most in judging these candidacies. The first has to do with restoring and promoting prosperity and sharing its fruits more evenly in a globalizing era that has suppressed wages and heightened inequality. Here the choice is not a close call. Mr. McCain has little interest in economics and no apparent feel for the topic. His principal proposal, doubling down on the Bush tax cuts, would exacerbate the fiscal wreckage and the inequality simultaneously. Mr. Obama's economic plan contains its share of unaffordable promises, but it pushes more in the direction of fairness and fiscal health. Both men have pledged to tackle climate change.

Mr. Obama also understands that the most important single counter to inequality, and the best way to maintain American competitiveness, is improved education, another subject of only modest interest to Mr. McCain. Mr. Obama would focus attention on early education and on helping families so that another generation of poor children doesn't lose out. His budgets would be less likely to squeeze out important programs such as Head Start and Pell grants. Though he has been less definitive than we would like, he supports accountability measures for public schools and providing parents choices by means of charter schools.

A better health-care system also is crucial to bolstering U.S. competitiveness and relieving worker insecurity. Mr. McCain is right to advocate an end to the tax favoritism showed to employer plans. This system works against lower-income people, and Mr. Obama has disparaged the McCain proposal in deceptive ways. But Mr. McCain's health plan doesn't do enough to protect those who cannot afford health insurance. Mr. Obama hopes to steer the country toward universal coverage by charting a course between government mandates and individual choice, though we question whether his plan is affordable or does enough to contain costs.

The next president is apt to have the chance to nominate one or more Supreme Court justices. Given the court's current precarious balance, we think Obama appointees could have a positive impact on issues from detention policy and executive power to privacy protections and civil rights.

Overshadowing all of these policy choices may be the financial crisis and the recession it is likely to spawn. It is almost impossible to predict what policies will be called for by January, but certainly the country will want in its president a combination of nimbleness and steadfastness -- precisely the qualities Mr. Obama has displayed during the past few weeks. When he might have been scoring political points against the incumbent, he instead responsibly urged fellow Democrats in Congress to back Mr. Bush's financial rescue plan. He has surrounded himself with top-notch, experienced, centrist economic advisers -- perhaps the best warranty that, unlike some past presidents of modest experience, Mr. Obama will not ride into town determined to reinvent every policy wheel. Some have disparaged Mr. Obama as too cool, but his unflappability over the past few weeks -- indeed, over two years of campaigning -- strikes us as exactly what Americans might want in their president at a time of great uncertainty.

On the second set of issues, having to do with keeping America safe in a dangerous world, it is a closer call. Mr. McCain has deep knowledge and a longstanding commitment to promoting U.S. leadership and values.

But Mr. Obama, as anyone who reads his books can tell, also has a sophisticated understanding of the world and America's place in it. He, too, is committed to maintaining U.S. leadership and sticking up for democratic values, as his recent defense of tiny Georgia makes clear. We hope he would navigate between the amoral realism of some in his party and the counterproductive cocksureness of the current administration, especially in its first term. On most policies, such as the need to go after al-Qaeda, check Iran's nuclear ambitions and fight HIV/AIDS abroad, he differs little from Mr. Bush or Mr. McCain. But he promises defter diplomacy and greater commitment to allies. His team overstates the likelihood that either of those can produce dramatically better results, but both are certainly worth trying.

Mr. Obama's greatest deviation from current policy is also our biggest worry: his insistence on withdrawing U.S. combat troops from Iraq on a fixed timeline. Thanks to the surge that Mr. Obama opposed, it may be feasible to withdraw many troops during his first two years in office. But if it isn't -- and U.S. generals have warned that the hard-won gains of the past 18 months could be lost by a precipitous withdrawal -- we can only hope and assume that Mr. Obama would recognize the strategic importance of success in Iraq and adjust his plans.

We also can only hope that the alarming anti-trade rhetoric we have heard from Mr. Obama during the campaign would give way to the understanding of the benefits of trade reflected in his writings. A silver lining of the financial crisis may be the flexibility it gives Mr. Obama to override some of the interest groups and members of Congress in his own party who oppose open trade, as well as to pursue the entitlement reform that he surely understands is needed.

It gives us no pleasure to oppose Mr. McCain. Over the years, he has been a force for principle and bipartisanship. He fought to recognize Vietnam, though some of his fellow ex-POWs vilified him for it. He stood up for humane immigration reform, though he knew Republican primary voters would punish him for it. He opposed torture and promoted campaign finance reform, a cause that Mr. Obama injured when he broke his promise to accept public financing in the general election campaign. Mr. McCain staked his career on finding a strategy for success in Iraq when just about everyone else in Washington was ready to give up. We think that he, too, might make a pretty good president.

But the stress of a campaign can reveal some essential truths, and the picture of Mr. McCain that emerged this year is far from reassuring. To pass his party's tax-cut litmus test, he jettisoned his commitment to balanced budgets. He hasn't come up with a coherent agenda, and at times he has seemed rash and impulsive. And we find no way to square his professed passion for America's national security with his choice of a running mate who, no matter what her other strengths, is not prepared to be commander in chief.

Any presidential vote is a gamble, and Mr. Obama's résumé is undoubtedly thin. We had hoped, throughout this long campaign, to see more evidence that Mr. Obama might stand up to Democratic orthodoxy and end, as he said in his announcement speech, "our chronic avoidance of tough decisions."

But Mr. Obama's temperament is unlike anything we've seen on the national stage in many years. He is deliberate but not indecisive; eloquent but a master of substance and detail; preternaturally confident but eager to hear opposing points of view. He has inspired millions of voters of diverse ages and races, no small thing in our often divided and cynical country. We think he is the right man for a perilous moment.