Strong was elected as a delegate to the Philadelphia Convention that drafted the U.S. Constitution in 1787. A committed Federalist, Strong opposed the idea of the Electoral College as a means of electing the president, instead supporting the idea that the legislature should choose him. Although he initially opposed proposals that the number of senators should be equal for all states, he eventually changed his mind, enabling passage of the Connecticut Compromise. To temper the power of the states, he introduced language requiring tax legislation to originate in the House of Representatives. Illness of his wife forced him to return to Massachusetts before the work was completed, so he did not sign the document. He was a vocal supporter of its adoption by the state's ratifying convention.