Jefferson included an anti-slavery clause in the rough draft of the Declaration of Independence. The exact circumstances of the passage’s removal may never be known; the historical record doesn't include details of the debates undertaken by the Second Continental Congress. What is known is that the 33-year-old Jefferson, who composed the Declaration between June 11 and June 28, 1776, sent a rough draft to members of a pre-selected committee, including John Adams and Benjamin Franklin, for edits ahead of its presentation to Congress. Between July 1 and July 3, congressional delegates debated the document, during which time they excised Jefferson’s anti-slavery clause.
Decades later, in his autobiography, Jefferson primarily blamed two Southern states for the clause’s removal, while acknowledging the North’s role as well.
"The clause...reprobating the enslaving the inhabitants of Africa, was struck out in compliance to South Carolina and Georgia, who had never attempted to restrain the importation of slaves, and who on the contrary still wished to continue it. Our Northern brethren also I believe felt a little tender under these censures; for tho' their people have very few slaves themselves, yet they had been pretty considerable carriers of them to others.”