But the conventional wisdom is wrong. The president retains the ability to do a great deal, especially in foreign policy; the question is whether he has the will and flexibility to use that power wisely.

To understand why Bush still has so much power, remember that the U.S. Constitution and political system give the executive most of the initiative in foreign-policy making. Congress’s powers are modest. The Senate must approve ambassadors and treaties, but few are sent its way so late in a president’s term. Congress also gets to declare war, but no formal declaration has been made in more than half a century. While Congress still must approve spending for foreign adventures, the president can still do a great deal without any explicit financial commitment.

What does this mean for Bush? In Iraq, he could propose a new policy that splits the difference between the surge, which isn’t working, and withdrawal by a fixed date, which could lead to chaos and harm America’s reputation. Such a compromise would cut the number of U.S. troops by more than half, scale back their combat role and relocate many away from Baghdad. It could win bipartisan backing and reduce military costs while still giving Iraq needed support.

On Iran, Bush could drop his insistence that Tehran make the first move (by stopping uranium enrichment) before bilateral talks are held. Instead, he could authorize his representative to meet with Iranian officials to negotiate verifiable limits to Iran’s enrichment program, which would leave Iran well short of a nuclear-weapons capability and give the world confidence that this was in fact the case. In return, the United States and others would reduce their economic sanctions. Such an approach might well succeed. And even if it didn’t, it would help clarify Washington’s remaining options—either to come to grips with a nuclear Iran (much as it has with North Korea) or to disrupt Tehran’s programs through military force. Both choices would have enormous consequences, but the point is that Bush remains largely free to make them.

The president could also strive to create conditions amenable to peace talks between Israelis and Palestinians. He should start with a speech laying out in detail what a comprehensive deal would look like, including elements to ensure the viability of a Palestinian state. This would give Palestinian moderates something to embrace and place radical rejectionists on the defensive.

Bush could help China, Japan and others create a regional framework for managing Asian relations. The president could also lay out a global approach to slowing climate change, including specific mechanisms to limit carbon production. Closer to home, Bush could close Guantánamo Bay and hold trials for the prisoners in the United States or their home countries.

Bush could even stake out positions on policies where congressional approval is needed. He could call for the phasing out of agricultural subsidies, for example, to remove an obstacle standing in the way of successful completion of the current global trade round; doing so would improve living standards for U.S. citizens and people in developing countries. Or he could back legislation that would reduce U.S. oil consumption, which would reduce the flow of funds to hostile regimes and help slow global warming. Bush might not persuade the Democrats in Congress to go along, but he could nonetheless change the debate and make it easier for his successor to finish what he started.

As all this suggests, the president retains considerable power to shape events. The real question is whether he will use it. What stands in the way is not the political calendar but bureaucratic politics and ideology. For the White House to change course now, it would have to rethink its resistance to diplomacy and multilateral institutions, revise some established policies and take on special interests, from the farm lobby to automakers. But the rewards would be huge. At stake is not only Bush’s legacy but the character of the country and the world he will bequeath to the 44th president. Neither the United States nor the rest of the planet would benefit from 18 months of drift.