Draper was a member of the Family Compact and Harrison was a moderate Reformer, the predecessor of the Liberal Party of Canada.

Harrison introduced amendments which watered down Robert Baldwin's resolutions calling for responsible government to make them acceptable to Sydenham.

However, it was Harrison who recommended to Sydenham's successor, Sir Charles Bagot, that Baldwin and Louis-Hippolyte Lafontaine be invited to form the next government.

Harrison served as provincial secretary in the new administration but resigned in 1843 to protest the movement of the capital from Kingston to Montreal.

He was elected again to the assembly in Kent in 1844 but resigned in 1845 to accept an appointment as judge of the Surrogate Court for the Home District.