Catalysis of the reaction: UDP-N-acetylgalactosamine + N-acetylneuraminyl-alpha-2,3-galactosyl-beta-oligosaccharide = UDP + N-acetylgalactosaminyl-N-acetylneuraminyl-alpha-2,3-galactosyl-beta-oligosaccharide.
UDP-GalNAc:Neu5Ac-alpha-2-Gal-beta-1-R beta-1,4-N-acetylgalactosaminyltransferase activity