  We study the propagation of bosonic strings in singular target space-times.
For describing this, we assume this target space to be the quotient of a smooth
manifold $M$ by a singular foliation ${\cal F}$ on it. Using the technical tool
of a gauge theory, we propose a smooth functional for this scenario, such that
the propagation is assured to lie in the singular target on-shell, i.e. only
after taking into account the gauge invariant content of the theory. One of the
main new aspects of our approach is that we do not limit ${\cal F}$ to be
generated by a group action. We will show that, whenever it exists, the above
gauging is effectuated by a single geometrical and universal gauge theory,
whose target space is the generalized tangent bundle $TM\oplus T^*M$.
