This year America has two first-class major-party candidates for the presidency, with experiences enough to fill novels. While acknowledging that any candidate endorsement involves a leap of faith, we support Sen. Barack Obama over his estimable Republican opponent, John McCain.

The Illinois Democrat’s self-discipline, calm, intelligence, experiences, eloquence and ability to reach out to a panorama of Americans with widely different backgrounds have impressed us. The Arizona Republican, for his part, has sometimes displayed an irritability and negativity unsuited to an office that combines the functions of head of government and head of state.

Senator McCain has criticized his opponent for allegedly having too little experience. But consider Mr. Obama’s knowledge of America at the neighborhood and at the national level. Consider how well he understands and articulates the challenges and opportunities of our heterogeneous world and his obvious capacity for empathy and his ability to listen. (That is not to say, of course, that we laud his associations with the Rev. Jeremiah Wright and some other dubious Chicagoans. But then, Mr. Obama, like Mr. McCain, has had a very complicated life.)

Mr. Obama was educated at Occidental and Columbia colleges and Harvard Law School, where he was president of the Harvard Law Review. His work in an international business consultancy, and then as a lawyer, writer, community organizer and politician has repeatedly demonstrated his ability to work with and inspire people in very different settings. And in his presidential race, he has shown an impressive management ability by organizing and running a vast and complicated campaign whose success would have seemed implausible two years ago.

And, yes, consider Senator Obama’s culturally complex national and international background, and that he has known both affluence and poverty. He has, in short, been informed by a very rich set of experiences, some very challenging emotionally and intellectually, that should strengthen his capacity for national and international leadership.

John McCain, of course, is an impressive leader — with a record for bravery and independence. But in his effort to gain the support of the Republican base, he has cast off some of the ideals that for a long time made him so attractive to us. While he used to be a deficit hawk, who warned about the effects on our over-indebted society of federal budget deficits, in this election cycle he has backed continued big tax cuts weighted to the wealthy. He has also supported some of the Bush administration’s constitutionally flawed policies in the “War on Terror.” His response to the credit crisis has been erratic, with several ill-considered schemes put forward. And he seems less likely to effectively address the urgent need for health-care reform and independence from fossil fuel than Mr. Obama.

Neither of the candidates’ economic plans add up: They both ignore the scary deficit and contain absurd promises (as in all such campaigns), but Senator Obama seems to us to be more likely to develop a coherent and effective program. Mr. Obama, whose advisers include the likes of Warren Buffett and Paul Volcker, has displayed more interest in and knowledge of economics than has Senator McCain, who thought that this election would be mostly about national security and foreign affairs instead of how to deal with a financial disaster. We suspect, by the way, that Messrs. Obama’s and McCain’s national-security and foreign policies in practice would not be nearly as different as some have predicted.

There is also the matter of vice-presidential selections, probably the most important one a presidential candidate makes. In this, the 72-year-old McCain has come up short. Alaska Gov. Sarah Palin, whom Senator McCain apparently chose to appeal to his party’s right wing, is intelligent and often engaging but has not yet shown the breadth of knowledge, the judgment or the temperament needed to be a good president. Senator Obama’s choice, Delaware Sen. Joseph Biden, however, has that knowledge and experience, however irritating his egotism.

The next president will have to deal with a Congress that, although almost certainly Democratic, will sometimes want to go its own way. And all successful American politicians must be willing to shift course and endlessly experiment in that broad center that Americans want to stay in.

“We do not know what the future will bring except that it will be different from any future we could predict,” said John Maynard Keynes. So above all, our choice comes down to broad themes and a sense of a candidate’s judgment, temperament and experience, and hence ability to lead the country as unforeseen events roll in. Thus we endorse Barack Obama.