In 1845, he was elected a member of the provincial house of representatives of Rio de Janeiro province, site of the national capital of the same name. Rio Branco rose to power within the province under the tutelage of Aureliano Coutinho, Viscount of Sepetiba—a veteran politician who held tremendous influence over the young and inexperienced Emperor Pedro II. He temporarily abandoned politics after Aureliano Coutinho's fall from grace and the subsequent dissolution of the Liberal Party.