Inconstant political support is a central problem for presidents, a problem of political authority. This article provides empirical evidence of the decline of political authority for American presidents over the last seventy years by examining several indicators comprising the related concept of political capital. Declining political capital lies at the core of the political authority problem besetting recent presidents. The evidence of declining political capital presented here reveals that none of Barack Obama's post-1965 predecessors solved the political authority problem. It is the central political challenge confronted by modern presidents and presently by Barack Obama.