An unscientific poll of 109 professional historians this year found that 61 percent rated President Bush as the worst president in American history.

A couple of others judged him second-worst, after James Buchanan, whose incompetence set the stage for the Civil War. More than 98 percent of the historians in the poll, conducted through the History News Network, viewed Mr. Bush’s presidency as a failure.

Mr. Bush’s presidency imploded not because of any personal corruption or venality, but largely because he wrenched the United States out of the international community. His cowboy diplomacy “defriended” the United States. He turned a superpower into a rogue country. Instead of isolating North Korea and Iran, he isolated us — and undermined his own ability to achieve his aims.

So here’s the top priority for President Barack Obama or President John McCain: We must rejoin the world.

There are three general ways in which we can signal a new beginning and “refriend” our allies:

• We should not only close the Guantánamo prison but also turn it into an international center for research on tropical diseases that afflict poor countries. It could thus become an example of multilateral humanitarianism.

The new president should also start a Truth Commission to investigate torture and other abuses during the “war on terror.” This should not be a bipartisan panel but a nonpartisan one, dominated by retired generals and intelligence figures like Brent Scowcroft or Colin Powell.

Such a panel would be respected as fair and authoritative in a way that one composed of bickering Democrats and Republicans would not, and it would underscore that we are eager to return to the norms of the civilized world.

• The new president also should signal that we will no longer confront problems just by blowing them up. The military toolbox is essential, but it shouldn’t be the first option for 21st-century challenges. You can’t bomb climate change.

We also have to pay far more attention to public diplomacy and outreach. Our Afghanistan and Pakistan policy is a mess in part because Osama bin Laden’s approval rating in Pakistan (34 percent) is almost double America’s (19 percent). You know we need a new approach when we lose a public relations competition to a fugitive mass murderer.

A new approach means a vigorous effort for peace in the Middle East. We also need to commit to negotiating with odious countries. President Clinton’s engagement policy toward North Korea was a constant headache, for Kim Jong Il was brutally repressive and tried to start a secret uranium program. But North Korea didn’t produce nuclear materials for a single weapon during Mr. Clinton’s years in office; under Mr. Bush, it has produced enough for a half dozen.

So here’s the score: Clinton diplomacy, 0 weapons; Bush fulmination, 6 weapons.

• We must cooperate with other countries on humanitarian efforts, including family planning. One of the Bush follies that has bewildered and antagonized our allies has been the vacuous refusal to support family planning through the United Nations Population Fund.

The upshot of the failure to support contraception has been millions of unwanted pregnancies and abortions. It’s difficult to think of any person alive today whose policies have led to more unnecessary abortions worldwide than Mr. Bush.

For all my criticisms, though, I would rank Mr. Bush more gently than those historians: I would peg him as second worst, after Buchanan. That’s because Mr. Bush has begun effective foreign-aid programs against AIDS and malaria that are saving millions of lives. His AIDS programs have transformed areas of southern Africa, but he so antagonized the world that America never gets adequate credit for this huge achievement.

Look, a friendlier, more multilateral policy will not solve the world’s problems. Iran isn’t going to give up its nuclear program because it likes us, and brawn is necessary to back up brains.

But without global political capital, we don’t have the leverage to organize more muscular persuasion. Without diplomatic heavy lifting, we can’t credibly threaten military heavy smashing.

In the aftermath of World War II, the United States led the international effort to construct global institutions to promote peace and prosperity. These included the United Nations, the World Bank and the International Monetary Fund, and they served our interests. Now, in the aftermath of the cold war, we need to rethink and refurbish this architecture for the next half century or more.

The United States needs to be a part of the International Criminal Court and should lead the push for a new climate change treaty, for example. The new president should be an architect of this emerging order, rather than AWOL as the Bush administration has been.

For eight years, the United States has been in self-imposed exile, and that is one reason Mr. Bush’s presidency has failed on so many levels. After Tuesday, let’s rejoin the world.