Senators were elected over a wide range of time throughout 1844 and 1845, and a seat may have been filled months late or remained vacant due to legislative deadlock.

The Democratic Party re-captured control of the Senate, gaining a net total of eleven seats from the Whigs.

Nathaniel P. Tallmadge had been re-elected in 1840 to the Class 1 seat (term 1839–1845), but resigned June 17, 1844, to become Governor of Wisconsin Territory.

Silas Wright Jr. had been re-elected in 1843 to the Class 3 seat (term 1843–1849), but resigned November 26, 1844, when elected Governor of New York.

Dickinson re-took his seat under the new credentials on January 27, 1845, and re-elected, remained in office until March 3, 1851, when his term expired.

Incumbent Daniel Sturgeon was re-elected by the Pennsylvania General Assembly to the United States Senate.