  We propose a theory in which the Standard Model gauge symmetry is extended by
a new $SU(2)_\ell$ group acting nontrivially on the lepton sector which is
spontaneously broken at the TeV scale. Under this $SU(2)_\ell$ the ordinary
leptons form doublets along with new lepton partner fields. This construction
naturally contains a dark matter candidate, the partner of the right-handed
neutrino, stabilized by a residual global $U(1)_\chi$ symmetry. We show that
one can explain baryogenesis through an asymmetric dark matter scenario, in
which generation of related asymmetries in the dark matter and baryon sectors
is driven by the $SU(2)_\ell$ instantons during a first order phase transition
in the early universe.
