The framers also devoted scant attention to the vice president's duties, providing only that he "shall be President of the Senate, but shall have no Vote, unless they be evenly divided" (Article I, section 3). In practice, the number of times vice presidents have exercised this right has varied greatly. John Adams holds the record at 29 votes, followed closely by John C. Calhoun with 28. Since the 1870s, however, no vice president has cast as many as 10 tie-breaking votes. While vice presidents have used their votes chiefly on legislative issues, they have also broken ties on the election of Senate officers, as well as on the appointment of committees in 1881 when the parties were evenly represented in the Senate.

The vice president's other constitutionally mandated duty was to receive from the states the tally of electoral ballots cast for president and vice president and to open the certificates "in the Presence of the Senate and House of Representatives," so that the total votes could be counted (Article II, section 1). Only a few happy vice presidents — John Adams, Thomas Jefferson, Martin Van Buren, and George Bush — had the pleasure of announcing their own election as president. Many more were chagrined to announce the choice of some rival for the office.

Several framers ultimately refused to sign the Constitution, in part because they viewed the vice president's legislative role as a violation of the separation of powers doctrine. Elbridge Gerry, who would later serve as vice president, declared that the framers "might as well put the President himself as head of the legislature." Others thought the office unnecessary but agreed with Connecticut delegate Roger Sherman that "if the vice-President were not to be President of the Senate, he would be without employment, and some member [of the Senate, acting as presiding officer] must be deprived of his vote."

Under the original code of Senate rules, the presiding officer exercised great power over the conduct of the body's proceedings. Rule XVI provided that "every question of order shall be decided by the President [of the Senate], without debate; but if there be a doubt in his mind, he may call for a sense of the Senate." Thus, contrary to later practice, the presiding officer was the sole judge of proper procedure and his rulings could not be turned aside by the full Senate without his assent.

The first two vice presidents, Adams and Jefferson, did much to shape the nature of the office, setting precedents that were followed by others. During most of the nineteenth century, the degree of influence and the role played within the Senate depended chiefly on the personality and inclinations of the individual involved. Some had great parliamentary skill and presided well, while others found the task boring, were incapable of maintaining order, or chose to spend most of their time away from Washington, leaving the duty to a president pro tempore. Some made an effort to preside fairly, while others used their position to promote the political agenda of the administration.

During the twentieth century, the role of the vice president has evolved into more of an executive branch position. Now, the vice president is usually seen as an integral part of a president's administration and presides over the Senate only on ceremonial occasions or when a tie-breaking vote may be needed. Yet, even though the nature of the job has changed, it is still greatly affected by the personality and skills of the individual incumbent.