The role of the presidency has changed in this century as power has shifted among the branches of government. In the formation of the Constitution and the government it supported, the Founding Fathers sought balance within the federal government itself through a separation of powers, the provision placing different governmental powers in the three branches of government--the executive, legislative, and judicial branches. This separation of powers is part of a system of checks and balances. Left out of this formulation is the public, which exercises power through the force of public opinion in the period between elections and at the ballot box during elections. The President comes into office with an agenda which he then tries to get implemented. This can be done in one of three ways: legislation can be introduced in Congress and passed by both houses; some efforts can be made through Executive Orders; and an Administration can pursue changes in the law through the courts by filing suits in the appropriate venue. The best way for the President to implement a domestic policy program is to push legislation through Congress rather than to turn to the courts because doing so creates a consensus and results in a stronger policy, one less likely to be challenged by Congress given that Congress was instrumental in formulating it.
The intent of the Framers of the Constitution was that the powers of the Executive and the Legislative branches be balanced (along with the Judicial, which can be omitted for the moment). At the beginning of this century, that balance was more or less in place, with shifts one way or the other over time. The power of the presidency was much increased by Franklin D. Roosevelt as he sought to gain control of the country's economic problems in the Depression. This power was only enhanced more by World War II, for in wartime the Executive Branch tends to gain power as Congress defers to the war-making powers...