 Haynes was elected to the Tennessee House of Representatives in 1845.As a legislator, he supported a repeal of the "quart" law (which banned the sale of liquor in quantities of less than one quart), tried to amend the bill chartering Jackson College to obtain funds for Washington College and Tusculum, and tried to amend a banking bill to establish branches of the state bank in each of the state's grand divisions.In 1847, he was elected to the Tennessee Senate.