“I thought I was serving my country, but I was only serving the rich and powerful people who stole my land,” he said.

In 2015, Mr. Peung Thy joined a small political party founded by a popular grass-roots campaigner named Kem Ley. But less than a year after the party came into existence, Mr. Kem Ley was shot dead as he was buying his morning coffee in Phnom Penh. Other activists have also been killed, particularly those investigating illegal trades like timber.

Back in Phnom Penh, Perk Chrep, a 30-year-old worker in Cambodia’s important garment industry, fretted that she had little choice in the electoral exercise. The line manager at her Chinese-owned factory, she said, had warned the seamstresses several times that if they did not come back to work with ink on their fingers, they need not return at all.

Ever since garment workers flocked to the opposition in the 2013 elections, Mr. Hun Sen has courted this demographic, regularly holding rallies where he handed out envelopes of cash.

But Ms. Perk Chrep, who makes $300 a month with overtime pay, said she did not want to sell her vote. She mourned the dissolution of the Cambodia National Rescue Party, which she said had worked to guarantee basic rights for garment workers.

Sitting in a single room devoid of furniture, Ms. Perk Chrep said that all she wanted to do was send a message to Mr. Hun Sen.

“I want him to reflect on what he has promised the people in Cambodia,” she said. “Does he really think he has achieved that much except for adding more years to his rule?”