(Why? Because I'm feeling rather pessimistic today.)
Whose Presidency will leave us with a better country in four to eight years, Barack Obama or John McCain?
The fact that people are seriously asking and trying to answer this question is proof that the American Constitutional system is horribly broken, possibly beyond repair. The President should have little or no power to do anything that would so drastically affect the situation in our country.
Congress is the preeminent branch of the federal government. The President and the Courts are bound by the laws of Congress as well as the Constitution, since the Executive exists to enforce the laws passed by the Legislature and the Judiciary exists to rule on whether or not particular instances of governmental activity or state and local law violate the laws passed by the Legislature. Congress is bound only by itself and the Constitution (since the Constitution grants it its powers, since it is in charge of its own internal laws and since it is in charge of trying impeachments).
Moreover, the scope of the power and authority of the federal government is itself proscribed by the Constitution. The federal government has only those powers explicitly given to it. The States have all powers except those explicitly denied to them. The States are sovereign in all areas but those areas where they gave up sovereignty to enter into union under the Constitution. So not only should Congress have a greater effect on the country than either the President or the Supreme Court, but State and local officials should have a greater effect on the life of their citizens than any federal official should.
The whole thing is upside-down and bass-ackwards. The only positive is that it will almost certainly fall apart sooner rather than later. The continental United States is far too large to be so centralized and survive. Its all a matter of scale.