One way to get past the magnificent charm, celebrated windiness, and political staying power of Senator Biden is through the lens of America’s war with Slobodan Milosevic, whom the gentleman from Delaware famously looked in the eye and accused of being a war criminal. Senator Obama’s choice for vice president turns out to be the archetype of what might be called the Kosovo Democrats. They are liberals who, during the 1990s, began to understand the necessity of the unilateral use of American force, even in the face of disapprobation at the United Nations, but changed their minds when the president defying the United Nations was a Republican and, in the war they initially supported, the going got tough.

The Kosovo Democrats supported President Clinton’s decision to bomb Serbia in 1999, even though the war to prevent the cleansing of Kosovo’s Albanians was not supported by a U.N. Security Council resolution. Declared the secretary-general at the time, Kofi Annan: “Unless the Security Council is restored to its preeminent position as the sole source of legitimacy on the use of force, we are on a dangerous path to anarchy.” Mr. Biden would have none of it. He said in response, “Nobody in the Senate agrees with that. There is nothing to debate. He is dead, flat, unequivocally wrong.”

This exchange is recounted in Ambassador Bolton’s memoir, “Surrender Is Not An Option.” Mr. Biden plays a role in that memoir because the senator from Delaware led the charge against Mr. Bolton in 2005 when Democrats prevented a floor vote on the nomination of the future ambassador to the United Nations. “My problem with you, over the years, has been, you’re too competent,” Mr. Bolton recounts Mr. Biden saying at one point during a colloquy on arms control in 2001. “I mean, I would rather you be stupid and not very effective.” He concluded by saying: “I think you are an honorable man and you are extremely competent.” Then he voted against Mr. Bolton.

Mr. Biden’s foreign policy schizophrenia is apparent in the run-up to the Battle of Iraq as well. He said at the time that he did not consider Saddam Hussein an immediate threat and believed that America’s top challenges ought to be North Korea and finishing the job against Al Qaeda in Afghanistan. Nevertheless, Mr. Biden voted for the war. With more than 100,000 American soldiers perched in Kuwait on January 31, 2003, Mr. Biden said in a speech before the World Affairs Council: “If we withdraw in these circumstances without a fundamental change in [Saddam’s] behavior, I have reached the conclusion that that is even more damaging to us than if we were to go with an anemic cast of the willing to take him down.”

This balancing act has been a hallmark of Mr. Biden’s approach to the current global war in the last seven years. In 2003, he said he believed Saddam was pursuing nuclear weapons and could acquire them within five years. Two years later, Mr. Biden made it a point to call out the Bush administration for misleading and deceiving the public on pre-war intelligence.

In early 2006, Mr. Biden made a push to send even more troops to Iraq, arguing, with Senator McCain, that the current force levels were not enough to protect civilians from terror militias running roughshod throughout Iraq. But when the president in 2007 embraced a strategy to send more troops and focus on protecting the civilian population, Mr. Biden skedaddled for the hills, plumping for a policy that would have effectively partitioned Iraq into three autonomous federal states.

When President Bush rolled out his strategy to send a surge of reinforcements for our beleaguered expedition in Iraq, Mr. Biden made a point to say how he would be lobbying his Republican colleagues in the Senate to oppose the strategy. Nonetheless, in the months of the early primary days when Mr. Biden campaigned for president in Iowa and New Hampshire, he chastised some of his Democratic colleagues on the trail for promising to withdraw the troops from Iraq at too rapid a pace.

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For those of us who maintained an enthusiasm for the Democratic Party until it marched off after Senator McGovern, the selection of Mr. Biden can be encouraging only in the relative sense. That is, compared to some Mr. Obama could have chosen, Mr. Biden is a step in the right direction. Nowhere in the party, however, do we see anything like the deep keel on foreign affairs that was put down by, say, George Meany or Scoop Jackson. Even if Mr. Obama had wanted one, nowhere is there in the Democratic Party a leader with the ability to maintain a politically incorrect position the way it was done by, say, Lane Kirkland for the Democrats, or, for the Republicans, by President Bush. There was one such figure among the Democrats in the past few years. But he was, in effect, expelled by the party in Connecticut. So Senator Lieberman is today an independent preparing to speak to the Republican convention in Minneapolis-St. Paul. It would be quite a statement if he were the man Mr. McCain turns to for a running mate to face off against Mr. Biden.