Serving in the House of Commons from 1741 to 1774 and again from 1775 to 1784, Conway became a leading old Whig, opposing the King's action against John Wilkes in 1763 and entering office with Lord Rockingham as Secretary of State for the Southern Department in 1765 before switching to the Northern Department the next year, serving until his resignation in 1768. In these offices, Conway sought to urge a moderate policy towards the American colonies, being the principal supporter of the repeal of the Stamp Act in 1766, and opposing the taxation policies of Chancellor of the Exchequer Charles Townshend. Following his resignation in January 1768, Conway returned to the military, and in 1772 was made a full general and Governor of Jersey. He remained an important figure in the Commons, opposing the British attempt to suppress the American Revolt, and his motion in March 1782 was partly responsible for the fall of the North government. He was rewarded with a cabinet position and the office of Commander-in-Chief in the new Rockingham ministry, but left the government a year later with the establishment of the Fox-North Coalition. His political career came to an end in 1784 when he lost his seat in parliament due to his opposition to the government of William Pitt.