Congress wishes to enact legislation prohibiting discrimination in the sale or rental of housing on the basis of the affectional preference or sexual orientation of the potential purchaser or renter. Congress wishes this statute to apply to all public and private vendors and lessors of residential property in this country, with a few narrowly drawn exceptions. The most credible argument for congressional authority to enact such a statute would be based upon the 
general welfare clause of Article I, Section 8, because the conduct the statute prohibits could reasonably be deemed to be harmful to the national interest.  commerce clause of Article I, Section 8, because, in inseverable aggregates, the sale or rental of almost all housing in this country could reasonably be deemed to have a substantial effect on interstate commerce.  enforcement clause of the Thirteenth Amendment, because that amendment clearly prohibits discrimination against the class of persons protected by this statute.  enforcement clause of the Fourteenth Amendment, because that amendment prohibits all public and private actors from engaging in irrational discrimination.