Union members and their political allies filled the streets of the Mexican capital Thursday night to condemn President Felipe Calderón's recent liquidation of a state-run power utility, a surprise move seen by many as an assault on organized labor.

Declaring the state-owned company so poorly managed as to be "unsustainable," Calderón on Saturday night authorized the seizure of Central Light and Power. He also deployed about 1,000 federal police officers in riot gear to enforce his decree; workers from another state-run power company swept in to take over the electric grid and keep the lights on.