[The president] shall have Power, by and with the Advice and Consent of the Senate, to make Treaties, provided two thirds of the Senators present concur; and he shall nominate, and by and with the Advice and Consent of the Senate, shall appoint Ambassadors, other public Ministers and Consuls, Judges of the supreme Court, and all other Officers of the United States…
While most of the Senate-related clauses of the Constitution are included in Article I, which creates the legislative branch of the federal government, it is Article II, section 2 that gives the Senate the exclusive right to provide advice and consent to the president on treaties and nominations. The concept of "advice and consent" can be traced back to Great Britain and the state governments and was a subject of debate during the Constitutional Convention. Some delegates believed that such a clause compromised the principle of separation of powers by allowing the legislative branch to infringe on the powers of the executive. In The Federalist, numbers 75 and 76, however, Alexander Hamilton argued that the provision afforded a necessary means of checks and balances.
The Constitution gives the Senate the power to approve, by a two-thirds vote, treaties negotiated by the executive branch. The Senate does not ratify treaties. Instead, the Senate takes up a resolution of ratification, by which the Senate formally gives its advice and consent, empowering the president to proceed with the ratification of the treaty. Early on, the Senate set a precedent in how it would exercise its advice and consent powers. When President George Washington visited the Senate Chamber in August 1789 to seek advice and consent on negotiating a treaty with Indian tribes, he became frustrated when the senators referred his questions to committee for further discussion. Neither Washington nor any of his successors would again confer with the Senate in person. It would take 130 years before another president of the United States would personally deliver a treaty to the Senate. On July 10, 1919, Woodrow Wilson asked for a quick consent to the Treaty of Versailles.
The Constitution also provides that the Senate shall have the power to accept or reject presidential appointees to the executive and judicial branches. This provision, like many others in the Constitution, was born of compromise. In debating the issue, the framers addressed concerns that entrusting the appointment power exclusively to the president would encourage monarchical tendencies. Additionally, as the Senate was to represent each state equally, its role offered security to the small states, whose delegates feared they would be overwhelmed by appointees sympathetic to the larger states.