U.S. Constitution – Article 1 Section 3

Immediately after they shall be assembled in Consequence of the first
Election, they shall be divided as equally as may be into three Classes. The
Seats of the Senators of the first Class shall be vacated at the Expiration of
the second Year, of the second Class at the Expiration of the fourth Year, and
of the third Class at the Expiration of the sixth Year, so that one third may
be chosen every second Year;

(and if Vacancies happen by Resignation, or otherwise, during
the Recess of the Legislature of any State, the Executive thereof may make
temporary Appointments until the next Meeting of the Legislature, which shall
then fill such Vacancies.) (The preceding words in parentheses were
superseded by the 17th Amendment, section
2.)

No person shall be a Senator who shall not have attained to the Age of
thirty Years, and been nine Years a Citizen of the United States, and who
shall not, when elected, be an Inhabitant of that State for which he shall be
chosen.

The Vice President of the United States shall be President of the Senate,
but shall have no Vote, unless they be equally divided.

The Senate shall chuse their other Officers,
and also a President pro tempore, in the
absence of the Vice President, or when he shall exercise the Office of
President of the United States.

The Senate shall have the sole Power to try all Impeachments. When sitting for that Purpose,
they shall be on Oath or Affirmation. When the President of the United States is
tried, the Chief Justice shall preside: And no Person shall be convicted without
the Concurrence of two thirds of the Members
present.

Judgment in Cases of Impeachment shall
not extend further than to removal from Office, and disqualification to hold
and enjoy any Office of honor, Trust or Profit under the United States: but
the Party convicted shall nevertheless be liable and subject to Indictment,
Trial, Judgment and Punishment, according to Law.

Last Modified: 16 Aug 2010