Nayib Bukele, the millennial president who reshaped El Salvador by cracking down on both gangs and civil liberties, looked poised to win another five years in office after polls closed on Sunday.

The electoral authorities had not released official results by Sunday night, but Mr. Bukele claimed victory in a post on X, saying he had won more than 85 percent of the vote.

Legal scholars say Mr. Bukele violated the Constitution of El Salvador by seeking a second consecutive term, but most Salvadorans don’t seem to care. Surveys showed that voters overwhelmingly supported his candidacy and were likely to maintain the ruling party’s supermajority, extending Mr. Bukele’s control over every lever of government for years.

Since imposing a state of emergency in the spring of 2022. the Bukele government has arrested tens of thousands of people with no due process, filled the streets with soldiers and suspended key civil liberties. But the gangs that once ruled over much of the country have been decimated — making the 42-year-old leader enormously popular.

“The majority of Salvadorans are in agreement that Bukele should stay,” said David Lobato, 38, outside a polling station in San Salvador, the capital. “He’s turned the country around. Things are different now.”

The five opposition candidates for president gained almost no traction in the polls. Among them were contenders from the right-wing Arena and leftist Farabundo Martí National Liberation Front parties that had once dominated Salvadoran politics for 30 years.