But his government withheld other essentials.

Dr. Arias said medical supplies, always scarce in La Vela, soon disappeared, hoarded until the May election. He said his superiors wanted to flood hospitals with supplies right before the vote, giving the impression that Mr. Maduro had fixed the country’s shortages.

“When the elections came, everything appeared: medicine, gas, dressings for bandages, injection serums,” he said. Residents in La Vela who had gone to the clinic confirmed it was suddenly supplied before the election.

The case of the oxygen tanks still weighs heavily on Dr. Arias.

“I argued with my colleagues over and over,” he said. “Yes, of course there was oxygen, but they didn’t let me use it.”

Ángel Villegas, La Vela’s opposition mayor, said he was denied medication, too, told that it was in short supply.

“There are a large number of services where you feel that, yes, they took into consideration the fact that you were in the opposition,” he said.

As Election Day neared, the doctors continued to fan out in support of Mr. Maduro.

“They come to your house, they ask you a series of questions, and you start to think, if I answer ‘no,’ they can cut me from health care,” said one patient, who declined to be named, fearing government reprisals. “It just leaves you overwhelmed.”

On May 20, Mr. Maduro was declared the winner, landing him a second term. For Dr. Arias, it was too much.