The powers of the president and the executive branch in general are found in Article II of the Constitution. For a full list of them, consult this link.
The most important of the president's powers include:
- Power to appoint judges, ambassadors, and high government officials. These powers give the president influence over the judiciary, foreign policy, and the executive branch.
- Power to be the commander-in-chief of the armed forces. This gives the president a great deal of power in the area of foreign affairs.
- Power to veto bills. This power is actually in Article I, but it is a major presidential power.
The president's major responsibility, as set out in Article II, is simply to "take Care that the Laws be faithfully executed." The president today has many more informal responsibilities than this in that he (and someday she) is expected to do things like proposing the political agenda for the Congress and ensuring that the economy will run smoothly. However, the responsibility of executing the laws is the only one that is actually explicitly set out in the Constitution.