  We recast the action principle of four dimensional General Relativity so that
it becomes amenable for perturbation theory which doesn't break general
covariance. The coupling constant becomes dimensionless (G_{Newton} \Lambda)
and extremely small 10^{-120}. We give an expression for the generating
functional of perturbation theory. We show that the partition function of
quantum General Relativity can be expressed as an expectation value of a
certain topologically invariant observable. This sets up a framework in which
quantum gravity can be studied perturbatively using the techniques of
topological quantum field theory.
