Six Republican incumbents lost re-election to Democrats:
Arizona: Republican incumbent Ralph H. Cameron lost to Democrat Carl Hayden.
Kentucky: Republican incumbent Richard P. Ernst lost to Democrat Alben W. Barkley.
Maryland: Republican incumbent Ovington E. Weller lost to Democrat Millard E. Tydings.
Missouri: Republican interim appointee George H. Williams lost to Democrat Harry B. Hawes both to finish the term and to the next term.
New York: Republican incumbent James W. Wadsworth, Jr. lost to Democrat Robert F. Wagner.
Oklahoma: Republican incumbent John W. Harreld lost to Democrat Elmer Thomas.
An additional Democratic seat was gained in a special election:
Massachusetts: Republican interim appointee William M. Butler lost to Democrat David I. Walsh.
Five Republican incumbents lost renomination, but their seats were held by Republicans:
Colorado: Republican incumbent Rice W. Means lost renomination to Republican challenger Charles W. Waterman, who then won the general election.
Illinois: Republican incumbent William B. McKinley lost renomination to Republican challenger Republican challenger Frank L. Smith, who then won the general election.
Oregon: Republican incumbent Robert N. Stanfield lost renomination to Republican challenger Frederick Steiwer, who then won the general election.
Pennsylvania: Republican incumbent George W. Pepper lost renomination to Republican challenger William S. Vare, who then won the general election.
Wisconsin: Republican incumbent Irvine L. Lenroot lost renomination to Republican challenger John J. Blaine, who then won the general election.
No Democratic incumbents lost re-election or renomination. The only change in a Democratic seat was in [|Alabama], where Democrat Oscar Underwood retired and was replaced by Democrat Hugo L. Black. No third party candidates won these elections. The sole third party incumbent was not up for election this year.
In these general elections, the winners were elected for the term beginning March 4, 1927; ordered by state. All of the elections involved the Class 3 seats.
Alabama
Arizona
Arkansas
California
Colorado
Connecticut
Florida
Georgia
Idaho
Illinois
Indiana
There were 2 elections in Indiana due to the October 14, 1925 death of Democrat Samuel M. Ralston.
