[1] A mentee of Chicago mayor Carter Harrison IV, Hoyne was tasked in his early political career with overseeing the city's Sixth Ward Democratic Organization.

[1] In 1903, after he was elected to a fourth consecutive term as mayor, Harrison appointed Hoyne as the city's Assistant Corporation Counsel.

He was up against six other candidates, including William Emmett Dever (supported by the Edward Fitzsimmons Dunne-led wing of the party), and J.J. Kern (supported by the Roger Charles Sullivan-led wing of the party).

[1] Hoyne unsuccessfully ran as an independent candidate in the 1919 Chicago mayoral election.

However, he lost the Democratic primary to Michael L. Igoe, who went on to be defeated in the general election by Republican Robert E.