  Barbero recently suggested a modification of Ashtekar's choice of canonical
variables for general relativity. Although leading to a more complicated
Hamiltonian constraint this modified version, in which the configuration
variable still is a connection, has the advantage of being real. In this
article we derive Barbero's Hamiltonian formulation from an action, which can
be considered as a generalization of the ordinary Hilbert-Palatini action.
