Who did President Jefferson originally give the task of leading the expedition to?

Thomas Jefferson had dreamed of exploring the West for at least 20 years before he even became President. In 1783 he had asked William Clark's brother, George Rogers Clark, to take on the challenge. George Rogers Clark was a well-known Revolutionary War hero, and Jefferson felt he was very suitable for the task. George politely declined however, and Jefferson though such an expedition would never get off the drawing table, but that all changed after purchasing the Louisiana territory years later.