East Asian regionalism is an on-going process, despite lacking much necessary “progress.” A glimmer of hope from the rise of China is now being shed on the prospect of East Asian regionalism, thanks to states clustering economically to China in a process as economic “power constellation.” Econophoria functions as a facilitator to the development process of East Asian regionalism. Given China’s reluctance and regional aspirations in building necessary institutions and requisite leadership, however, this paper infers some possible forms of leadership that the US can develop regarding institutional bargaining. The US is perceived to be a critical player in finalizing East Asian regionalism for it is the only country that can render necessary leadership and therefore institutional building capability. If, as a regional player, the US wishes to recover its lost credibility and undermined trust, then the time is ripe for proper action. The article will briefly review the notion of power aggregation and power constellations so as to provide an analytical framework. It will then examine the prospect of an emerging regional order in the aftermath of China’s power aggregation. In the following section, the article will assess the US position on the question of regional leadership and East Asian regionalism. The paper will conclude with possible strategic choices for the US in realizing regional aspirations.