From a strictly political perspective, it's a loser. They won't get enough votes to make it happen, and so all it will do is inflame white racists to try.
There are also solid substantive issues with it. For example, how do you administer such reparations? Do you require people to demonstrate slave ancestry, genealogically? Are reparations pro-rated based on proportion of slave ancestry? Also, isn't any reparation number going to necessarily be felt as a kick in the teeth by some, since no number is going to be sufficient to compensate for generations of forced labor. Isn't it also going to set a precedent where reparations are also owed to other mistreated groups -- e.g., descendants of Native Americans who had their lands taken, their ancestors imprisoned or murdered, etc. What about descendants of victims of American colonialism in places like the Philippines, or descendants of people we bombed in Vietnam, and so on? It just seems like a big can of worms.