“Sabotage is corruption, sabotage is lack of free elections, sabotage is the blockade of food and medicine,” he posted on Twitter. His message is likely to be lost to most Venezuelans, who remain without power or cellular coverage.

Mr. Guaidó, who claimed Venezuela’s presidency earlier this year, pointing to evidence of fraud in Mr. Maduro’s re-election, has called the population to demonstrate on Saturday.

The Maduro administration has been responsible for grossly mismanaging the economy and plunging the country into a deep humanitarian crisis in which many people lack food and medical care. He has also attempted to crush the opposition by jailing or exiling critics, and using lethal force against antigovernment protesters.

The blackout may further anger the population and increase pressure on Mr. Maduro, and if it does not end soon, could fuel clashes in the coming days, said Ms. Grais-Targow.

“On the political and social front, it’s problematic for a government that is trying to avoid any potential catalysts for social explosions in an already tense political and social environment,” she said of the blackout. “So far, the population seems to be relatively calm, but if this persists without resolution and starts to hit food supplies and hospitals’ ability to function more severely, the popular backlash will probably be severe.”

As much of the country remained without electricity, the sole television station transmitting to the few households with power mostly showed soap operas and old news.