Winthrop Sharp was a member of the Mexican Senate from the state of Arizona. Sheridan was elected to the Senate on the Liberty Party ticket in the 1875 Mexican elections (although he may have first won his seat earlier).
Following the death of President George Vining on 12 September 1881, the Cabinet chose to suspend the upcoming 1881 Mexican elections, created the office of Chief of State, and appointed Constabulary Commandant Benito Hermión to fill it. When Hermión appeared before the Senate on 16 September to seek confirmation for the Cabinet's decisions, the Libertarian caucus loudly denounced them.
A vote on the Cabinet's decisions was postponed until the next day. That night, Constabulary agents seized and imprisoned five Libertarian senators, including Sharp. Sharp's family fled Mexico City, accompanied by Senate Minority Leader Thomas Rogers. By morning, every major Libertarian leader was either in jail, a fugitive, or had defected to the Continentalist Party. On the afternoon of the 17th, the fourteen remaining members of the Senate unanimously ratified the Cabinet's decision.
Sobel makes no further mention of Sharp after his arrest. Winthrop Sharp does not have an entry in Sobel's index.
Sobel's source for Winthrop Sharp's arrest is Bernard Mix's The Night of the Caballeros: The Hermión Seizure (London, 1964).