Washington did not hold an office during the period, but he remained perhaps the most important man in the new United States. He had been very disillusioned with the ability of Congress to supply his army during the war, but remained circumspect about the government in the immediate aftermath of independence. A number of politicians, including James Madison, John Jay and especially Alexander Hamilton, recognized his importance and sought to gain his support for major reforms to the Articles. In 1785, he hosted a conference between officials from Maryland and Virginia at his Mount Vernon home. This meeting led to the Annapolis Convention, which, while largely a failure, paved the way for what would become the Constitutional Convention in 1787. Washington, of course, was president of that convention. So he played a central, if rather quiet role in bringing about the end of the Articles of Confederation.
Source: John Ferling, A Leap in the Dark: The Struggle to Create the American Republic (New York: Oxford University Press, 2003)274-277.