In 1792 he was sent by George Washington to London to negotiate a new treaty with the British. The treaty he returned with, known as Jay's Treaty deeply displeased many in the US. Jay became so unpopular that he once commented that he could travel from Boston to Philadelphia sorely by the light of his burning effigies. When no alternative treaties could be negotiated, Jay's treaty was accepted as tolerable, and was signed by Washington.
In 1794, Jay was sent on another diplomatic mission, this time to France. While in France, he was elected governor of New York State. He resigned from the Court, and served as governor of New York until 1800. President John Adams then renominated him to the court; the Senate quickly confirmed him, but he declined, citing his own poor health and the court's lack of "the energy, weight, and dignity which are essential to its affording due support to the national government."
Jay was also the fifth President of the Continental Congress, and thus the leader of what was to become the United States, from December 10, 1778, until September 27, 1779. He was preceded in office by Henry Laurens and succeeded by Samuel Huntington.
Jay did not attend the Constitutional Convention, but contributed five essays to what later became the Federalist Papers.