Although Butler served in the General Assembly from 1776 to 1789, his most significant political accomplishments came at the national level. In 1787 the legislature elected Butler to both the Confederation Congress and the constitutional convention scheduled to meet later that spring in Philadelphia. In the constitutional debates, Butler generally supported proposals for a strong central government, a single executive, and wealth rather than population as the basis of representation. He also championed South Carolina interests, especially slavery, and vigorously opposed the three-fifths compromise, arguing that slaves represented property wealth and should be counted fully for purposes of representation.