Carr participated in the investigation of the JFK assassination . He led the state probe and cooperated with the Warren Commission , which was appointed by President Johnson to determine the circumstances leading to Kennedy 's death . Carr said that the combined state-federal probe was a success and that both teams worked well together . Years later , at the dedication of the Bob Bullock Texas State History Museum in Austin , Carr recalled that the investigation into the Kennedy assassination was thorough and professional : " It makes me sad that it the assassination happened , but it does n't make me sad to share with the interested people of Texas about what this investigation revealed and how thorough it was and how nonpolitical it was . " As the sitting attorney general in 1966 , Carr challenged Republican incumbent John Goodwin Tower ( 1925 – 1991 ) for the United States Senate . In doing so , Carr was unable to seek a third two-year term as Attorney General . Carr was defeated , and was only the second Texas Democrat in state history to lose a statewide general election since Reconstruction ; the first having been William A. Blakley of Dallas in his 1961 loss to Tower . Senator Tower received 842,501 votes ( 56.7 percent ) to Carr 's 643,855 ( 43.3 percent ) . In winning , Tower lost the majority of the rural districts to Carr , who had the strong support of both President Lyndon B. Johnson and Governor John B. Connally , Jr. , while Connally was still a Democrat . Tower , though , ran strongly in the larger urban areas . At the time of his loss to Tower , Carr had been voted the nation 's best state attorney general by his peers
JFK assassination
Assassination of John F. Kennedy
Waggoner Carr