In the first district, Democratic Senator James M. Love resigned on July 1, 1856, causing a vacancy in his seat that was filled by special election.

[13] In the twentieth district, Democratic Senator Theophilus Bryan was originally declared the winner.

[15] In the twenty-fourth district, Democratic Senator John G. Shields died on June 25, 1856, causing a vacancy in his seat.

Prior to the 1856 election, nearly all Whigs switched political party affiliation to become Republicans.

To claim control of the chamber from Democrats, the Republicans needed to garner 19 Senate seats.