No - *Constitutional* Congress - the British had been defeated - circa 1789 - they were forming the backbone and laws and principles of a new nation - and the issue of slavery and whether or not it would exist in the new republic was *very* much an issue. Anti-slavery groups were broadly petitioning the fledgling government to abolish it once and for all, because if we were to base the new nation on a principle of equality, we had to extend it to all men. And it proved to be a tender spot for those framing the new Constitution, because they knew they could NOT outlaw it if they wanted the keep the southern states in the Union, *especially* Virginia, the wealthiest state. They had war debts to pay, and the nation could not afford to be broken up.
So what did they do? In the final document, they kept quiet about it.
It was a very big issue for at least the next 20 years, through the War of 1812, with groups actively trying to shut it down, such as the Quakers in PA. It was just inconceivable to the Americans that if we were eliminating royalty, aristocracy, and all the trappings of station and class - why did we still cling to slavery? When it became obvious that the South would NOT relinquish slavery - the efforts of the anti-slavery groups appeared similarly to those of today's anti-abortion crowd - if they can't change the LAWS, maybe they can influence public opinion, although they were always trying to influence laws.
Check it out - the anti-slavery movement is an interesting read - and there were those at the time of Washington who predicted civil war, if the issue didn't get resolved.