Candidates (O)

Karl O’Lessker

• 1964 – Indiana’s 6th congressional district (D) – lost

Joseph M. O’Loughlin

• 1976 – Massachusetts’ 9th congressional district (I) – lost

Joseph Christopher O’Mahoney

• 1934 – United States Senate (Wyoming) (Special) (D) – won
• 1934 – United States Senate (Wyoming) (D) – won
• 1940 – United States Senate (Wyoming) (D) – won
• 1946 – United States Senate (Wyoming) (D) – won
• 1952 – United States Senate (Wyoming) (D) – lost
• 1954 – United States Senate (Wyoming) (Special) (D) – won
• 1954 – United States Senate (Wyoming) (D) – won

Patrick J. O’Malley

• 1948 – Massachusetts’ 1st congressional district (D) – lost

Stephen P. O’Malley, Jr.

• 2004 – Massachusetts’ 6th congressional district (R) – lost

Thomas David Patrick O’Malley

• 1928 – Wisconsin’s 5th congressional district (D) – lost
• 1930 – Wisconsin’s 5th congressional district (D) – lost
• 1932 – Wisconsin’s 5th congressional district (D) – won
• 1934 – Wisconsin’s 5th congressional district (D) – won
• 1936 – Wisconsin’s 5th congressional district (D) – won
• 1938 – Wisconsin’s 5th congressional district (D) – lost

Bill O’Mara

• 1978 – Nevada’s at large congressional district (R) – lost

Eugene J. O’Mara

• 1928 – New Jersey’s 10th congressional district (D) – lost

William ‘Liam’ O’Mara

• 2020 – California’s 42nd congressional district (D) – lost

Edward S. O’Meara, Jr.

• 1988 – Maine’s 1st congressional district (R) – lost

John R. O’Meara

• 1958 – Michigan’s 3rd congressional district (D) – lost

O’Meara

• 1948 – Missouri’s 12th congressional district (S) – lost

David C. O’Neal

• 1980 – United States Senate (Illinois) (R) – lost

Gladys L. O’Neal

• 1968 – California’s 1st congressional district (AI) – lost

James O’Neal

• 1920 – New York’s 10th congressional district (S) – lost

John O’Neal

• 1976 – South Carolina’s 2nd congressional district (I) – lost

Maston E. O’Neal, Jr.

• 1964 – Georgia’s 2nd congressional district (D) – won
• 1968 – Georgia’s 2nd congressional district (D) – won
• 1968 – Georgia’s 2nd congressional district (D) – won

Maston Emmet O’Neal, Jr.

• 1934 – Kentucky’s 3rd congressional district (D) – won
• 1936 – Kentucky’s 3rd congressional district (D) – won
• 1938 – Kentucky’s 3rd congressional district (D) – won
• 1940 – Kentucky’s 3rd congressional district (D) – won
• 1942 – Kentucky’s 3rd congressional district (D) – won
• 1944 – Kentucky’s 3rd congressional district (D) – won
• 1946 – Kentucky’s 3rd congressional district (D) – lost

W. R. O’Neal

• 1926 – United States Senate (Florida) (R) – lost

A. F. O’Neil

• 1928 – Ohio’s 14th congressional district (D) – lost

Frank M. O’Neil

• 1962 – Pennsylvania’s 23rd congressional district (D) – lost

James N. O’Neil

• 2000 – Pennsylvania’s 12th congressional district (Ref.) – lost

Patrick M. O’Neil

• 1972 – New York’s 27th congressional district (CON) – lost

Pete O’Neil

• 2002 – Nevada’s 3rd congressional district (I) – lost

Bill O’Neill

• 2008 – Ohio’s 14th congressional district (D) – lost

Bruce Michael O’Neill

• 1988 – California’s 5th congressional district (R) – lost

Dan O’Neill

• 2016 – New Jersey’s 7th congressional district (L) – lost

Edward Leo O’Neill

• 1934 – New Jersey’s 11th congressional district (D) – lost
• 1936 – New Jersey’s 11th congressional district (D) – won
• 1938 – New Jersey’s 11th congressional district (D) – lost

Eugene T. O’Neill

• 1946 – New York’s 1st congressional district (D, American Labor) – lost

Francis G. O’Neill

• 1940 – Massachusetts’ 13th congressional district (D) – lost

Francis P. O’Neill

• 1942 – Massachusetts’ 12th congressional district (R) – lost

G. Darrell O’Neill

• 1938 – New Jersey’s 14th congressional district (S) – lost

Harry Patrick O’Neill

• 1948 – Pennsylvania’s 10th congressional district (D) – won
• 1950 – Pennsylvania’s 10th congressional district (D) – won
• 1952 – Pennsylvania’s 10th congressional district (D) – lost

Brian James O’Neill II

• 1990 – Illinois’ 19th congressional district (Solidarity) – lost

James F. O’Neill (Massachusetts)

• 1952 – Massachusetts’ 9th congressional district (D) – lost
• 1954 – Massachusetts’ 9th congressional district (D) – lost

James F. O’Neill (Michigan)

• 1962 – Michigan’s 17th congressional district (R) – lost

John O’Neill

• 1970 – United States Senate (Ohio) (SL) – lost
• 1972 – Ohio’s 23rd congressional district (SL) – lost
• 1976 – United States Senate (Ohio) (I) – lost

Joseph B. O’Neill

• 1942 – California’s 3rd congressional district (D) – lost

Lottie Holman O’Neill

• 1930 – United States Senate (Illinois) (IR) – lost

Megan O’Neill

• 1992 – Michigan’s 9th congressional district (R) – lost
• 1994 – Michigan’s 9th congressional district (R) – lost

Patrick O’Neill

• 1988 – Nevada’s 1st congressional district (L) – lost

Paul J. O’Neill

• 1964 – Florida’s 3rd congressional district (R) – lost

Thomas Phillip O’Neill, Jr.

• 1952 – Massachusetts’ 11th congressional district (D) – won
• 1954 – Massachusetts’ 11th congressional district (D) – won
• 1956 – Massachusetts’ 11th congressional district (D) – won
• 1958 – Massachusetts’ 11th congressional district (D) – won
• 1960 – Massachusetts’ 11th congressional district (D) – won
• 1962 – Massachusetts’ 8th congressional district (D) – won
• 1964 – Massachusetts’ 8th congressional district (D) – won
• 1966 – Massachusetts’ 8th congressional district (D) – won
• 1968 – Massachusetts’ 8th congressional district (D) – won
• 1970 – Massachusetts’ 8th congressional district (D) – won
• 1972 – Massachusetts’ 8th congressional district (D) – won
• 1974 – Massachusetts’ 8th congressional district (D) – won
• 1976 – Massachusetts’ 8th congressional district (D) – won
• 1978 – Massachusetts’ 8th congressional district (D) – won
• 1980 – Massachusetts’ 8th congressional district (D) – won
• 1982 – Massachusetts’ 8th congressional district (D) – won
• 1984 – Massachusetts’ 8th congressional district (D) – won

Vincent E. O’Neill

• 1952 – Michigan’s 5th congressional district (D) – lost

William Michael O’Neill

• 2010 – Ohio’s 14th congressional district (D) – lost

Gerald O’Reilly

• 1946 – New York’s 26th congressional district (American Labor) – lost

Kathleen F. O’Reilly

• 1980 – Michigan’s 2nd congressional district (D) – lost

Maurice O’Reilly

• 1950 – Iowa’s 6th congressional district (D) – lost

Michael A. O’Reilly

• 2016 – New York’s 5th congressional district (R, CON) – lost

T. Bronson O’Reilly

• 1956 – New York’s 1st congressional district (D, Liberal) – lost