As others have noted, the Declaration wouldn't have changed anything about the slave trade one way or another. Jefferson didn't fight for his clause either. In this as in other things he was more about poses and appearances than following through.
Of course, Congress voted to end the importation of slaves from abroad while Jefferson was president. The Constitution allowed Congress to do so after January 1, 1808, and it would probably have happened whoever was president. Jefferson deserves some credit, I guess, but one also has to take in to account his later views on slavery if one wants to pass judgment on him.
The next year Adams, speaking out against a bill to emancipate slaves in Massachusetts, said that the issue was presently too divisive, and so the legislation should “sleep for a time.” (Henry Wiencek 2004).
That was actual abolition which went beyond what Jefferson advocated at that point. It was also wartime, and the fate of independence hung by a thread. After the war was over Massachusetts courts ruled slavery invalid based on language in the 1780 state constitution that was largely drafted by ... John Adams.
If Adams was wrong in 1777 he was wrong, but through most of Jefferson's own career Thomas Jefferson also very much wanted anti-slavery legislation to "sleep," even favoring the expansion of slave-owning territory under the specious theory that diffusion would make the institution weaker.
He was a complicated man with different facets in his thought and character, some admirable, others not. I guess you can say that about many people, but it's something "Jeffersonians" haven't always wanted to face up to.
Over the years, I have lost some respect for Jefferson.
His actions in both of Washington’s administrations, from a viewpoint of loyalty and respect to George Washington (which should have been unquestioned) paint him in a less than positive light. Jefferson had been spreading rumors behind the scenes that Washington was a feeble, doddering old man who was making decisions based on the whispers in his ear from people like Hamilton, whom he detested.
For his own personal reasons, he was undermining the legitimacy of the very administration he was a member of.
Washington found out via an unimpeachable source that Jefferson was behind some of that, and confronted him directly and personally with that information. After that, their relationship in private was non-existent, and in public, was limited to polite exchanges.
His admiration and support for the French Revolution was disturbing to me as well, as he had plenty of knowledgable people telling him exactly what was going on over there, yet he persisted.
All in all, I do (to an extent) view Jefferson as the forefather of today’s Democrats, though their desire to destroy this country and mold it in their model sets them far, far apart from him.
All that said, it is hard not to admire Jefferson for his impressive intellect and written communication skills. He was remarkable in that respect.
Thomas Jefferson, designated writer of the first draft of the Declaration, inserted clauses condemning the Crown for forcing the growth of the slave trade, and calling for a formal cessation of the trade itself. He was making the statement that one of the issues prompting the separation of the colonies was the ongoing British government's efforts to thwart or reverse efforts in the colonies to exit the slave trade.
It is thus documented fact that Jefferson authored the first formal protestation against slavery in the written records of this country's foundation.
Although some of the signers were active in anti-slavery efforts on the local levels, no other member of the 56 signers had a record of opposition to the slave question at the proceedings.
Beginning with John Adams and Benjamin Franklin (slave owner), two of the most well known of the ‘subcommittee” that would submit the first draft, they did not object nor did the others of the committee, Livingston of New York and Sherman of Connecticut, so it passed on to the delegates as a whole.
It is a fact that Jefferson's clauses did not pass delegate approval, and therefore it must be said that Jefferson's effort to extinguish the slave trade was rebuked by the delegates. Aside from giving a "I have a dream" speech, I am not sure what option Jefferson had to advance the issue in that setting
Some of the delegates from Georgia and South Carolina were opposed to any slave trade reduction, and according to Jefferson's notes and the comments of others, there were the same objections from some Northern state delegates who did not want the trade interrupted.
Clearly Thomas Jefferson was the single, outspoken advocate of the elimination of the slave trade, when others would not risk taking that position.
Prime examples of this reticence were John Adams who wanted the issue to "remain asleep" (despite your attempted explanations without sourcing); Livingston; the orator of record, Franklin, who would not support Jefferson; John Hancock (slave owner) of Massachusetts, who would not offer support; and John Jay, (slave owner) who later came to Jefferson's opinion on the issue.