Joseph S. Nye Jr. is a University Distinguished Service Professor at Harvard. This article and the accompanying sidebar are adapted from his upcoming book, Presidential Leadership and the Creation of the American Era.

The 21st century began with an extraordinary imbalance in world power. The United States was the only country able to project military force globally; it represented more than a quarter of the world economy, and had the world’s leading soft-power resources in its universities and entertainment industry. America’s primacy appeared well established.

Americans seemed to like this situation. In the 2012 presidential campaign, both major-party candidates insisted that American power was not in decline, and vowed that they would maintain American primacy. But how much are such promises within the ability of presidents to keep? Was presidential leadership ever essential to the establishment of American primacy, or was that primacy an accident of history that would have occurred regardless of who occupied the Oval Office?

Leadership experts and the public alike extol the virtues of transformational leaders—those who set out bold objectives and take risks to change the world. We tend to downplay “transactional” leaders, whose goals are more modest, as mere managers. But in looking closely at the leaders who presided over key periods of expanding American primacy in the past century, I found that while transformational presidents such as Woodrow Wilson and Ronald Reagan changed how Americans viewed their nation’s role in the world, some transactional presidents, such as Dwight D. Eisenhower and George H. W. Bush, were more effective in executing their policies....

Related Links

• Joseph Nye: In Defense of Transactional Presidents (HNN)