In the terms of the presidency the true power lies in their ability to influence others to facilitate their legislative goals. Presidents differ in terms of their ability to influence the conduct of the men who make up government. The ability to influence then becomes the mark of leadership. According to Richard Neustadt, the power of the president is the "power to persuade." Within my answer I will discuss the president's persuasive powers in relation to Congress and the legislative process.
Many scholars have researched the president's influence on the final stages of the legislative process. However, it is the initial stages of the congressional agenda setting that the president gains a substantial amount of his power. Even though the president cannot formally introduce legislation to Congress, his party members frequently act as his conduit in the U.S. Capitol. Presidents initiate legislation in a variety of ways.
Perhaps the most formal and constitutionally proscribed way for the president to initiate legislation is through the State of the Union Address. In 1964, Johnson sent Congress a series of bills to address poverty and civil rights. A second venue for presidential initiatives are special policy addresses. Sometimes these occur in dramatic settings like when Reagan introduced his bill to permit school prayer in front of the National Association of Evangelicals. Other times the initiative is introduced in a setting very much like the State of the Union Address, like in 1973, when Nixon gave three separate speeches to a joint session of Congress on the administration's efforts to deal with the energy crisis. Sometimes the president will not expend the energy, resources, or political capital to initiate a piece of legislation, instead using cabinet officials or other high placed executive officials to champion the cause. Such was the case when Carter's Agriculture Secretary Bob Bergland introduced the administration's crop insurance proposal.