Upon his return, Franklin was elected president of the state executive council, the equivalent of governor. More importantly, he served as a delegate to the Constitutional Convention held in Philadelphia. At 81, he was the oldest delegate. As a resident of the city, he invited delegates to his garden where they could get a respite from debates. In this role of symbolic host and at the convention, Franklin helped to promote a spirit of compromise. He played an instrumental role in ensuring the acceptance of the Connecticut Compromise, which created one chamber of the legislature based on representation, the House of Representatives, and another based on equal representation of states, the Senate. In so doing, Franklin helped to resolve a core issue at the heart of the convention, whether the new nation would be a confederation of states or a unified nation.

More comfortable with democracy than most delegates, Franklin successfully spoke out against property requirements for the right to vote and argued for a congressional power of impeachment. Isaacson says that he delivered a “remarkable closing address” that was “a testament to the virtue of intellectual tolerance and to the evil of presumed infallibility” (457). After having spent a lifetime laying the foundations for a democratic republic, Franklin signed the document.