The 1928 United States Senate elections were elections that coincided with the presidential election of Republican Herbert Hoover. The 32 seats of Class 1 were contested in regular elections, and special elections were held to fill vacancies. The strong economy helped the Republicans to gain seven seats from the Democrats.
Senate Majority leader, Republican Charles Curtis of Kansas, was not up for election this cycle, but he was elected U.S. Vice President. He resigned March 3, 1929, so his seat was vacant at the beginning of the next Congress until April 1, 1929, when a Republican was appointed to continue the term.
Gains, losses, and holds
Retirements
Two Republicans and one Democrat retired instead of seeking re-election.
{| class="wikitable sortable plainrowheaders"
|-
! scope="col" |State
! scope="col" |Senator
! scope="col" |Replaced by
|-
! Connecticut
| |
| |
|-
! Missouri
| |
| |
|-
! New Mexico (special)
| |
| |
|}
Defeats
Seven Democrats sought re-election but lost in the primary or general election.
{| class="wikitable sortable plainrowheaders"
|-
! scope="col" |State
! scope="col" |Senator
! scope="col" |Replaced by
|-
! Delaware
| |
| |
|-
! Maryland
| |
| |
|-
! New Jersey
| |
| |
|-
! Ohio (special)
| |
| |
|-
! Rhode Island
| |
| |
|-
! Texas
| |
| |
|-
! West Virginia
| |
| |
|}
Disqualification
Two Republicans were elected in 1926, but disqualified from taking office. One resigned on February 9, 1928, and the seat was filled in the 1928 election. One resigned December 6, 1929 and the seat was filled by appointment.
{| class="wikitable sortable plainrowheaders"
|-
! scope="col" |State
! scope="col" |Senator
! scope="col" |Replaced by
|-
! Illinois
| |
| |
|-
! Pennsylvania
| |
| |
|}
Post-election changes
{| class="wikitable sortable plainrowheaders"
|-
! scope="col" |State
! scope="col" |Senator
! scope="col" |Replaced by
|-
! New Jersey
| |
| |
|-
! Ohio
| |
| |
|-
! Kentucky
| |
| |
|-
! Tennessee
| |
| |
|-
! Wyoming
| |
| |
|}
Change in composition
Before the elections
At the beginning of 1928.
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| colspan=10 align=right | Plurality ↓
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Elections result
{| class="wikitable" style="text-align:center" width=800px
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| rowspan=2 | R<br /><br />
|-
| colspan=9 align=right | Majority →
|-
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{|
|- valign=top
! Key
|
{| class=wikitable
|-
| align=center width=35px | D
| Democratic
|-
| align=center width=35px | FL
| Farmer–Labor
|-
| align=center width=35px | R
| Republican
|-
| align=center width=35px | V
| Vacant
|}
|}
Race summary
Special elections during the 70th Congress
In these special elections, the winner were seated during 1928; ordered by election date.
{| class=wikitable
|- valign=bottom
! rowspan=2 | State
! colspan=3 | Incumbent
! rowspan=2 | Results
! rowspan=2 | Candidates
|-
! Senator
! Party
! Electoral history
|-
! Idaho<br />(Class 3)
| John Thomas
| | Republican
| 1928
| Frank R. Gooding (R) died June 24, 1928, and Thomas was appointed June 30, 1928, to continue the term.<br />Interim appointee elected November 6, 1928.
| nowrap |
|-
! Illinois<br />(Class 3)
| colspan=3 | Vacant
| | 1926 Senator-elect Frank L. Smith (R) had been disqualified and resigned February 9, 1928.<br />New senator elected November 6, 1928.<br />Republican hold.
| nowrap |
|-
! Michigan<br />(Class 1)
| Arthur Vandenberg
| | Republican
| 1928
| Woodbridge N. Ferris (D) died March 23, 1928, and Vandenberg was appointed to continue the term.<br />Interim appointee elected November 6, 1928.<br />Winner was also elected to the next term, see below.
| nowrap |
|-
! New Mexico<br />(Class 1)
| Bronson M. Cutting
| | Republican
|1927
| | Interim appointee did not run to finish the term, but was elected to the next term, see below.<br />New senator elected November 6, 1928.<br />Republican hold.
| nowrap |
|-
! Ohio<br />(Class 3)
| Cyrus Locher
| | Democratic
| 1928
| | Frank B. Willis (R) died March 30, 1928, and Locher was appointed to continue the term.<br />Interim appointee lost nomination.<br />New senator elected November 6, 1928.<br />Republican gain.
| nowrap |
|}
Elections leading to the 71st Congress
In these general elections, the winners were elected for the term beginning March 4, 1929; ordered by state.
All of the elections involved the Class 1 seats, unless otherwise indicated.
{| class=wikitable
|- valign=bottom
! rowspan=2 | State
! colspan=3 | Incumbent
! rowspan=2 | Results
! rowspan=2 | Candidates
|-
! Senator
! Party
! Electoral history
|-
! Arizona
| Henry F. Ashurst
| | Democratic
| 1912<br />1916<br />1922
| Incumbent re-elected.
| nowrap |
|-
! California
| Hiram Johnson
| | Republican
| 1916<br />1922
| Incumbent re-elected.
| nowrap |
|-
! Connecticut
| George P. McLean
| | Republican
| 1911<br />1922
| | Incumbent retired.<br />New senator elected.<br />Republican hold.
| nowrap |
|-
! Delaware
| Thomas F. Bayard Jr.
| | Democratic
| 1922 <br />1922
| | Incumbent lost re-election.<br />New senator elected.<br />Republican gain.
| nowrap |
|-
! Florida
| Park Trammell
| | Democratic
| 1916<br />1922
| Incumbent re-elected.
| nowrap |
|-
! Indiana
| Arthur Raymond Robinson
| | Republican
| 1926
| Incumbent re-elected.
| nowrap |
|-
! Maine
| Frederick Hale
| | Republican
| 1916<br />1922
| Incumbent re-elected.
| nowrap |
|-
! Maryland
| William Cabell Bruce
| | Democratic
| 1922
| | Incumbent lost re-election.<br />New senator elected.<br />Republican gain.
| nowrap |
|-
! Massachusetts
| David I. Walsh
| | Democratic
| 1926
| Incumbent re-elected.
| nowrap |
|-
! Michigan
| Arthur Vandenberg
| | Republican
| 1928
| Interim appointee elected.<br />Winner was also elected to finish the current term, see above.
| nowrap |
|-
! Minnesota
| Henrik Shipstead
| | Farmer–Labor
| 1922
| Incumbent re-elected.
| nowrap |
|-
! Mississippi
| Hubert D. Stephens
| | Democratic
| 1922
| Incumbent re-elected.
| nowrap |
|-
! Missouri
| James A. Reed
| | Democratic
| 1910<br />1916<br />1922
| | Incumbent retired.<br />New senator elected.<br />Republican gain.
| nowrap |
|-
! Montana
| Burton K. Wheeler
| | Democratic
| 1922
| Incumbent re-elected.
| nowrap |
|-
! Nebraska
| Robert B. Howell
| | Republican
| 1922
| Incumbent re-elected.
| nowrap |
|-
! Nevada
| Key Pittman
| | Democratic
| 1913 <br />1916<br />1922
| Incumbent re-elected.
| nowrap |
|-
! New Jersey
| Edward I. Edwards
| | Democratic
| 1922
| | Incumbent lost re-election.<br />New senator elected.<br />Republican gain.
| nowrap |
|-
! New Mexico
| Bronson M. Cutting
| | Republican
|1927
| Interim appointee elected.<br />Winner was not elected to finish the current term, see above.
| nowrap |
|-
! New York
| Royal S. Copeland
| | Democratic
| 1922
| Incumbent re-elected.
| nowrap |
|-
! North Dakota
| Lynn Frazier
| | Republican
| 1922
| Incumbent re-elected.
| nowrap |
|-
! Ohio
| Simeon D. Fess
| | Republican
| 1922
| Incumbent re-elected.
| nowrap |
|-
! Pennsylvania
| David A. Reed
| | Republican
| 1922 <br />1922 <br />1922
| Incumbent re-elected.
| nowrap |
|-
! Rhode Island
| Peter G. Gerry
| | Democratic
| 1916<br />1922
| | Incumbent lost re-election.<br />New senator elected.<br />Republican gain.
| nowrap |
|-
! Tennessee
| Kenneth McKellar
| | Democratic
| 1916<br />1922
| Incumbent re-elected.
| nowrap |
|-
! Texas
| Earle B. Mayfield
| | Democratic
| 1922
| | Incumbent lost renomination.<br />New senator elected.<br />Democratic hold.
| nowrap |
|-
! Utah
| William H. King
| | Democratic
| 1916<br />1922
| Incumbent re-elected.
| nowrap |
|-
! Vermont
| Frank L. Greene
| | Republican
| 1916<br />1922
| Incumbent re-elected.
| nowrap |
|-
! Virginia
| Claude A. Swanson
| | Democratic
| 1910 <br />1911 <br />1912 <br />1916<br />1922
| Incumbent re-elected.
| nowrap |
|-
! Washington
| Clarence Dill
| | Democratic
| 1922
| Incumbent re-elected.
| nowrap |
|-
! West Virginia
| Matthew M. Neely
| | Democratic
| 1922
| | Incumbent lost re-election.<br />New senator elected.<br />Republican gain.
| nowrap |
|-
! Wisconsin
| Robert M. La Follette Jr.
| | Republican
| 1925
| Incumbent re-elected.
| nowrap |
|-
! Wyoming
| John B. Kendrick
| | Democratic
| 1916<br />1922
| Incumbent re-elected.
| nowrap |
|}
Closest races
Twelve races had a margin of victory under 10%:
{| class="wikitable sortable"
! State
! Party of winner
! Margin
|-
! New York
| data-sort-value=-0.5 | Democratic
| 1.2%
|-
! Rhode Island
| data-sort-value=-0.5 | Republican (flip)
| 1.3%
|-
! West Virginia
| data-sort-value=-0.5 | Republican (flip)
| 1.5%
|-
! Missouri
| data-sort-value=-0.5 | Republican (flip)
| 4.0%
|-
! Montana
| data-sort-value=-0.5 | Democratic
| 6.4%
|-
! Washington
| data-sort-value=-0.5 | Democratic
| 6.9%
|-
! Wyoming
| data-sort-value=-0.5 | Democratic
| 7.4%
|-
! Massachusetts
| data-sort-value=-0.5 | Democratic
| 8.1%
|-
! Connecticut
| data-sort-value=-0.5 | Republican
| 8.3%
|-
! Arizona
| data-sort-value=-0.5 | Democratic
| 8.6%
|-
! Maryland
| data-sort-value=-0.5 | Republican (flip)
| 8.9%
|-
! Illinois
| data-sort-value=-0.5 | Republican (flip)
| 9.6%
|}
New Mexico was the tipping point state with a margin of 15.4%.
Arizona
California
Michigan
First-term Democrat Woodbridge N. Ferris died March 23, 1928.
On March 31, 1928, Governor Fred W. Green appointed 44-year-old Republican Arthur H. Vandenberg to fill the vacancy, pending a special election. Green considered resigning so he could be appointed to the vacancy. He also considered several other candidates, including former governors Albert Sleeper and Chase Osborn. In addition, Green considered Representative Joseph W. Fordney, who would have been a placeholder until the election for the remainder of Ferris' term. Green finally decided upon Vandenberg, who immediately declared his intention to stand for election to both the short, unexpired term and the full six-year term. Both the special and the general elections were held the same day, November 6, 1928.