"The American presidency is designed to disappoint. Each candidate must promise things that are beyond his power to deliver. No candidate could expect to be elected by emphasizing how little power the office actually has and how voters should therefore expect little from him. So candidates promise great, transformative programs. What the winner actually can deliver depends upon what other institutions, nations and reality will allow him. Though the gap between promises and realities destroys immodest candidates, from the founding fathers' point of view, it protects the republic. They distrusted government in general and the office of the president in particular...Presidents make history, but not on their own terms. They are constrained and harried on all sides by reality. In selecting a president, it is important to remember that candidates will say what they need to say to be elected, but even when they say what they mean, they will not necessarily be able to pursue their goals. The choice to do so simply isn't up to them. There are two fairly clear foreign policy outlooks in this election. The degree to which the winner matters, however, is unclear, though knowing the inclinations of presidential candidates regardless of their ability to pursue them has some value."
Comment: I've long believed the true power of the Presidency is in the "bully pulpit," i.e. his ability to shape public debate (or perceptions) on an issue or to set national goals by virtue of the prestige of the office. I completely agree with Friedman's assessment of the President's ability to influence foreign affairs and I think he does a very good job at providing historical examples and relevant context. On the domestic front, however, I think the President has greater power to effect domestic policies if only by his ability to issue directives that dictate how Executive Branch agencies implement and enforce laws/policies. In this regard, Obama has had a dramatic impact on the country especially given the relative dysfunction of Congress.