Library of Congress. Congressional Research Service.
Abstract
Vacancies in Congress occur due to the death, resignation, or declination (refusal to serve) of a Senator or Representative, or as the result of expulsion or exclusion by either house. The Constitution requires that vacancies in both houses be filled by special election, but in the case of the Senate, it empowers state legislatures to provide for temporary appointments by the state governor until special elections can be scheduled. This report describes this process