The controversial question of whether to allow additional slave states into the United States coincided with the growing stature of the Declaration. The first major public debate about slavery and the Declaration took place during the Missouri controversy of 1819 to 1821. Anti-slavery Congressmen argued that the language of the Declaration indicated that the Founding Fathers of the United States had been opposed to slavery in principle, and so new slave states should not be added to the country. Pro-slavery Congressmen led by Senator Nathaniel Macon of North Carolina argued that the Declaration was not a part of the Constitution and therefore had no relevance to the question.