He entered by the side door.

From American Sphinx; The Character of Thomas Jefferson by Joseph J. Ellis.  Page 33.

Given his subsequent role in the Continental Congress and then in shaping the course of the American Revolution, his selection to serve on the Virginia delegation in Philadelphia was a fortunate accident. Jefferson was not elected to the original delegation in 1774; he was not considered a sufficiently prominent figure to be included with the likes of George Washington, Patrick Henry, Edmund Pendleton and Peyton Randolph. In 1775, however, he was chosen as a potential substitute for Randolph—Jefferson was regarded as Randolph’s political godson—in anticipation of Randolph’s decision to abandon his post at Philadelphia in order to assume leadership of what was regarded as the more important business back in Virginia. It would be fair to say that Jefferson made the list of acknowledged political leaders in the Old Dominion, but just barely, and largely because of his ties by blood and patronage with the Randolph circle. If his arrival in Philadelphia in June 1775 marked his entry into national affairs, he entered by the side door.