He spent one of last days of 2019 delivering presents to children in La Guaira, trailed by two government minders on motorbikes. In a lengthy interview between toy drops, he said his wife, Fabiana Rosales, and their toddler are followed even to their daughter’s preschool.

The rented apartment they share in a middle-class neighborhood in Caracas is half-empty, the home of a man who seems unsure where he will sleep tomorrow. The television is on the floor, child’s toys are stuffed in a corner, and the walls are bare, save for a large portrait of a Venezuelan nun named María de San José, known for aiding the ill.

Like many Venezuelans in the capital, he has running water about two hours a day.

At one point, when he raised the topic of his mother, who left the country for medical treatment that she could not find in Venezuela, his eyes turned red and he began to cry. “Of course I miss her,” he said.

Mr. Guaidó’s popularity has declined significantly in the last year, according to polling from the Caracas firm Datanálasis. But he remains the most popular politician in the country, according to the firm.

And in an interview, the firm’s director, José Gil Yepes, said Mr. Guaidó’s popularity may rise in the coming weeks, “because of all the things the government did wrong” on Sunday.

Mayrely Calderón, 39, a pharmacist, was among those who remained faithful to Mr. Guaidó. “He’s the one who will help us get rid of Maduro,” she said.

Julie Turkewitz and Ana Vanessa Herrero reported from Caracas. Lara Jakes reported from Washington.