Bowdoin was elected to the provincial assembly in 1753 and served there until named to the governor's council in 1756. Although at first supportive of the royal governor, his politics became more radical as British colonial policy became increasingly unpopular, and Bowdoin believed those policies would have a negative effect on the New England economy. Personal factors may also have played a role in Bowdoin's shift in views: John Temple, the local customs commissioner and Bowdoin's son in law, was embroiled in nasty disputes with Governor Francis Bernard in the 1760s. By 1769 Bowdoin was one of the principal spokesmen of the opposition to the governor on the council. In that year Bernard rejected Bowdoin's renewed election to the council. Bowdoin, however, was instrumental in causing Bernard's downfall from office. Private letters critical of the provincial government that Bernard had written were published in 1769 to great outrage. Bowdoin rebutted the charges and claims made in Bernard's letters, and published a highly polemic pamphlet arguing for Bernard's removal that was sent to the colonial secretary, Lord Hillsborough.