Joseph Nye's The Paradox of American Power deals with the American dilemma in today's world. Too strong to be truly challenged, yet too weak to go at it alone (as a quick glance at Bush's policies and failures confirms). According to Nye this is the case for a variety of reasons, most importantly the fading unipolar world. Remnants still exist, militarily most of all, but Nye separates the world in three chess boards (a military one, an economic one and a transnational one) only one of which features a dominating USA on top (you can guess which). Further eroding American power are transnational developments such as information flow, which lead to states in general being less capable of solving problems on their own.
The only way to preserve American (benign of course) hegemony is a concept Nye introduced in the 1990s called soft power (as opposed to hard military power). Soft power describes one's capability to 'get[...] others to want what you want.' Considering the impressive array of cultural and political appeal that the United States still possesses (apart from the usually cited Hollywood movies, one need only glance at the fuss made of Obama's inauguration outside of the US), Nye sees a distinct possibility that American hegemony can be prolonged significantly in this manner. For me personally, a large part of this argument is wishful thinking, beginning with the benign American hegemony (examples of its far less benign aspects abound I believe) soft power is exactly not what the US owns in abundance currently. In fact the Bush administration has been highly successful in eroding this kind of power and the good-will extended to Obama as of right now will undoubtedly change with the first unpopular decision of his government (say American support of an Israeli attack on Iranian nuclear sites or extended excursions into Waziristan in order to stabilize the situation in Afghanistan).
While I find the concept of soft power and its impact on international relations quite appealing (Zivilmacht Europa) and relevant and agree with Nye's basis of analysis, his criticism of American emphasis on defense over diplomatic budgets (16:1) for example, I cannot share his optimistic view concerning American capabilities to preserve their hegemony. Even assuming that Obama will reclaim some (or all) of the soft power lost under his predecessor, that will not change the fact that a variety of actors have begun to act as regional hegemons (the EU, China, Brazil). The US cannot counter this movement and while it will remain the most important voice on the international scene for a long time to come it cannot allow itself to even try to go at it alone anymore.