The 17 th Amendment, which provided for direct election of the Senate, also gave states the option of filling Senate vacancies by election or by temporary gubernatorial appointment:
When vacancies happen in the representation of any State in the Senate, the executive authority of such State shall issue writs of election to fill such vacancies: Provided, That the legislature of any State may empower the executive thereof to make temporary appointments until the people fill the vacancies by election as the legislature may direct. This report reviews the constitutional origins of the appointments provision and its incorporation in the 17 th Amendment. Latest Developments in Senate Vacancies

Two Senate vacancies occurred late in the 112 th Congress, due to the death of Senator Daniel K. Inouye of Hawaii, and the resignation of Senator Jim DeMint of South Carolina. Two more have occurred to date 113 th Congress, due to the resignation of Massachusetts Senator John F. Kerry and the death of New Jersey Senator Frank R. Lautenberg. Detailed information on these vacancies follows below in alphabetical order. Senator Inouye, who had served since 1963, was also President pro tempore of the Senate at the time of his death. In accord with Hawaiian law, Governor Neil Abercrombie announced on December 26 that he would appoint Lieutenant Governor Brian E. Schatz to serve in his place until the vacancy is filled by a special election in 2014. Senator Schatz was sworn in on December 27, 2012. The winner of the special election will serve until the term expires in 2017. On January 30, Massachusetts Governor Deval Patrick announced the appointment of William (Mo) Cowan, and advisor and former chief counsel and chief of staff to the governor, as interim Senator. Senator Cowan, who was sworn in on February 7, 2013, and served until the special election winner was certified and sworn in. In accordance with Massachusetts law, which requires a special election to fill the seat for the balance of the term between 145 and 160 days following the original vacancy, Secretary of the Commonwealth William F. Galvin scheduled a special primary election for April 30, followed by a special general election on June 25. Representative Markey won the special election, and was sworn in on July 16. He will serve the balance of the term, which expires in 2015. The New Jersey Statutes Annotated vests the governor with authority to make temporary appointments to fill Senate vacancies, with the appointed incumbent serving until a general or special election. On June 6, the governor announced his appointment of New Jersey Attorney General Jeffrey S. Chiesa to fill the vacancy and serve until the special election. The winner of the special election will serve the balance of the term, which expires in 2015. In accord with South Carolina law, Governor Nikki Haley announced on December 17 that she would appoint Representative Tim Scott to serve in his place until the vacancy is filled by a special election in 2014. The winner of the special election will serve until the term expires in 2017. Senator DeMint resigned effective January 1, 2013, and Senator Scott was sworn in on January 3. At the time of this writing, the Senate's records currently identify 193 appointments to the office of U.S. Filling Vacancies by Special Election

Oregon, Rhode Island, and Wisconsin currently provide that Senate vacancies be filled only by special elections. Rhode Island in 2009 required that any Senate vacancy be filled by special election only. These provisions are intended to ensure that the appointing governors respect the results of the previous election by selecting a temporary replacement who will either be of the same political party as the prior incumbent, or who has been endorsed or "nominated" by the prior incumbent's party apparatus. State Legislation Since 2009

Following controversies that arose in connection with appointments to fill Senate vacancies in 2008 and 2009, particularly with respect to the Illinois Senate vacancy, proposals to eliminate or curtail gubernatorial power to fill Senate vacancies by appointment were introduced in a number of state legislatures. Rhode Island in 2009 eliminated the governor's appointment authority, and provided expedited procedures for special elections. The special election was ultimately held on January 19, 2010, and state Senator Scott Brown was chosen to serve for the balance of the term, which expired on January 3, 2013. 21 would have required that all Senate vacancies be filled by special election.
United States Senators serve a term of six years. Vacancies occur when an incumbent Senator leaves office prematurely for any reason; they may be caused by death or resignation of the incumbent, by expulsion or declination (refusal to serve), or by refusal of the Senate to seat a Senator-elect or -designate.
This report provides information on current vacancies in the Senate, the constitutional origins of the Senate vacancy clause, the appointment process by which most vacancies are filled, and related contemporary issues. It will be revised and updated to reflect current developments in vacancies, appointments, and special elections.
Since December 2012, four vacancies have occurred in the Senate. They are identified below in alphabetical order by state.
In Hawaii, Senator Daniel K. Inouye, who was also President pro tempore of the Senate, died on December 17, 2012. Hawaii Governor Neil Abercrombie appointed Lieutenant Governor Brian E. Schatz to serve in his place until the vacancy is filled by a special election in 2014. Senator Schatz was sworn in on December 27, 2012. The winner of the special election will serve until the term expires in 2017.
In Massachusetts, Senator John F. Kerry resigned from the Senate on February 1, 2013, to assume the office of U.S. Secretary of State. The vacancy was filled by expedited special election procedures enacted in connection with the 2009 death of Senator Edward M. Kennedy. On January 30, Massachusetts Governor Deval Patrick announced the appointment of William (Mo) Cowan, to serve until the special election, which was scheduled for June 25. Senator Cowan was sworn in on February 7 and served until the winner of the special election was sworn in. Representative Edward J. Markey won the special election; he was sworn in on July 16, and will serve for the balance of the term, which expires in 2015.
In New Jersey, Senator Frank R. Lautenberg died June 3, 2013. New Jersey Governor Chris Christie set a special primary election for August 13, and a special general election for October 16. On June 6, the governor announced his appointment of New Jersey Attorney General Jeffrey S. Chiesa to fill the vacancy and serve until the special general election is held. The winner of the special election will serve for the balance of the term, which expires in 2015.
In South Carolina, Senator Jim DeMint resigned from the Senate on January 1, 2013, to assume the presidency of The Heritage Foundation. South Carolina Governor Nikki Haley appointed Representative Tim Scott to serve in his place until the vacancy is filled by a special election in 2014. Senator Scott was sworn in on January 3. The winner of the special election will serve until the term expires in 2017.
The use of temporary appointments to fill Senate vacancies is an original provision of the U.S. Constitution, found in Article I, Section 3, clause 2. The practice was revised in 1913 by the 17th Amendment, which provided for direct popular election of Senators, replacing election by state legislatures; it specifically directed state governors to "issue writs of election to fill such vacancies." The amendment also preserved the appointment option by authorizing state legislatures to empower governors to make temporary appointments pending a special election."
Since 1913, most states have exercised this option, authorizing their governors to fill Senate vacancies by temporary appointments. Some, however, limit the governor's power: appointed Senators in Arizona must be of the same political party as the prior incumbent, while in Hawaii, Utah, and Wyoming, the governor must choose a replacement from names submitted by the prior incumbent's party. In Connecticut and Oklahoma, the governor may make a temporary appointment in limited circumstances, and Oregon, Rhode Island, and Wisconsin require vacancies to be filled only by special election.
As a result of controversies that arose concerning appointments to Senate vacancies following the 2008 presidential election, legislation and a constitutional amendment that would have required all Senate vacancies to be filled by special election were introduced in the 111th Congress. None of these measures reached the floor of either chamber, however, and no comparable measures have been introduced since that time.
Since 2009, three states have substantially modified their vacancy procedures. Connecticut significantly restricted the governor's appointment power in such instances; Rhode Island eliminated it entirely, requiring that all future Senate vacancies be filled by special election; and Massachusetts modified its election-only requirement to reinstate gubernatorial appointment within an expedited special election process.