Bayard was elected to the
U.S. Senate in a special election on
November 7 1922, to fill the vacancy caused by the resignation of
U.S. Senator Josiah O. Wolcott. On the same day he was also elected for the full term to follow, in both instances defeating incumbent
Republican U.S. Senator T. Coleman du Pont, who had been appointed. During this term, he served in the
Democratic minority in the last session of the
67th Congress, and in the
68th 69th, and
70th Congress.
Bayard lost his bid for a second full term in 1928 to
Republican John G. Townsend, Jr., the former
Governor. He then lost another bid for a second full term in 1930 to incumbent
Republican U.S. Senator Daniel O. Hastings. In all, Bayard served one term and part of another, from
November 2 1922 to
March 4 1929, during the administrations of
U.S. Presidents Warren G. Harding and
Calvin Coolidge. Subsequently, he resumed his law practice in
Wilmington.