“The fate of Castro-ism may be at play in Venezuela,” Mr. Pardo said. “What we were not able to topple in Cuba, we may be able to topple there.”

Venezuelan opposition members’ resentment of Cuba stems partly from a deal under which their oil-rich country ships about $4 billion worth of crude oil to Cuba each year. In return, Cuba has sent thousands of doctors, dentists, technicians and sports coaches to work in Venezuela. Critics question how the value of those workers is calculated and point to problems in some of the social programs they work in, but many among Venezuela’s poor praise the Cuban presence, especially the doctors.

“It’s a great benefit,” said Marisol Echenique, 34, who on a recent morning stopped at a free neighborhood clinic operated by Cuban doctors, where she was given medicine for a stomach problem. “We can come here at any hour and depend on the Cubans.” She added that a niece takes dance lessons with a Cuban instructor through a separate government program.

Still, even among supporters of the relationship, there are occasional culture clashes.

“I value the Cuban doctors,” said Arizay Vegas, 40, waiting at a clinic staffed by Cuban doctors in Caracas. She recalled rushing to the clinic at 4 a.m. about a year ago, when her 2-year-old granddaughter fell out of bed and cut her head. “Here it’s very fast, and the treatment is good,” she said.

But when the Cuban doctor in charge of the clinic asked a reporter to leave because he did not have permission to interview patients, Ms. Vegas became indignant.

“We’re not in Cuba, we’re in Venezuela,” Ms. Vegas said. “I’m free to say whatever I want.”

The opposition is deeply suspicious of Cuba’s influence over policy and government decisions. Venezuela’s president, Nicolás Maduro, frequently praises the Castros in public speeches. When Mr. Chávez was ailing from cancer he went to Cuba for his surgery. And in the weeks before his death last year, Havana seemed almost to have become a de facto seat of Venezuela’s government, as a stream of top officials jetted there for meetings.

Beyond that, there is a sense among some in the Venezuelan opposition that the country, with its shortages of basic products and long lines, is becoming more like Cuba by the day.