Motivic Steenrod problem away from the characteristic

In topology, the Steenrod problem asks whether every singular homology class is the pushforward of the fundamental class of a closed oriented manifold. Here, we introduce an analogous question in algebraic geometry: is every element on the Chow line of the motivic cohomology of X the pushforward of a fundamental class along a projective derived-lci morphism? If X is a smooth variety over a field of characteristic p 0, then a positive answer to this question follows up to p-torsion from resolution of singularities by alterations. However, if X is singular, then this is no longer necessarily so: we give examples of motivic cohomology classes of a singular scheme X that are not p-torsion and are not expressible as such pushforwards. A consequence of our result is that the Chow ring of a singular variety cannot be expressed as a quotient of its algebraic cobordism ring, as suggested by the first-named-author in his thesis.