But on Monday afternoon, a populist force that in one incarnation or another has dominated every previous election this century claimed its own victory.
A partial count showed that the populist party, Pheu Thai, had so far collected the largest number of parliamentary seats on offer, which party officials said was a more important metric than the popular vote. The party represents the interests of Thaksin Shinawatra, a polarizing former prime minister as beloved by the rural poor as he is disdained by the establishment elite.
In the initial tally released on Monday afternoon, Pheu Thai had won 137 seats in the Lower House, compared with 97 for the pro-military party, Palang Pracharat, according to the Election Commission.
Yet the truth is that in Thailand, a nation with a stunted democracy strangled by complicated rules designed to perpetuate the military’s power, neither the popular vote nor the number of seats in this election is the true barometer of power.
Forces loyal to Prayuth Chan-ocha, the leader of the junta that orchestrated that coup, said he appeared poised to continue as prime minister, even though the party that nominated him, Palang Pracharat, was in second place in the contest for 500 seats in the Lower House.
Because the country’s military-drafted Constitution ensures that the 250-member Senate is entirely appointed by the military, Mr. Prayuth may be able to count on enough votes from both sides of Parliament to keep the top job. In an unusual twist to a parliamentary democracy, a candidate for prime minister in Thailand does not have to be an elected member of Parliament.
Purawich Watanasukh, a research fellow at King Prajadhipok’s Institute in Thailand, said he was “quite surprised with Palang Pracharat’s performance.” Mr. Purawich was among many analysts to have predicted that Mr. Prayuth’s perceived lack of popularity might affect the military party’s performance.
But support for the junta was stacked even before voting began. And the vote on Sunday was filled with reports of irregularities and concerns about repeated delays in announcing the results.
A full unofficial count of Sunday’s vote is not expected until late this week.
Uttama Savanayana, Palang Pracharat’s party leader, said in a news conference on Monday afternoon that “we have stated from the beginning that any party that gets the most votes is able to form a government.”
On Friday, Mr. Prayuth, a former army chief with an ambivalent attitude toward democracy, spoke of his commitment to his homeland. “I love Thailand, and I would die for this country,” he said at a political rally.
On Monday afternoon, the Election Commission delayed for the third time releasing its unofficial count of Sunday’s polls. Such postponements have never occurred before, Thai election experts say.
Before the voting began, the Election Commission, which was appointed by the junta, said it would have preliminary results counted by around 8 p.m. Sunday. But late that evening, Ittiporn Boonprakong, the chairman of the Election Commission, said that counting would stop for the night and that the results would be released at 10 a.m. Monday.
“I don’t have a calculator,” he said in response to queries about the intricacies of the balloting.
That deadline was later changed to 2 p.m. Then the Election Commission said results would be published at 4 p.m., but only for 350 of the 500 Lower House seats.
Winners of the other 150 seats may be announced on Friday, Nut Laosisavakul, the commission’s deputy secretary general, said on Monday afternoon.
It is not clear what prompted this latest delay. The calculation for who will fill these 150 seats, which represent parties rather than constituencies, is complicated. But with irregularities mounting, election monitors are nervous.
“My understanding is that the Election Commission has an obligation to continue counting the ballots through the night, so this is potentially problematic or illegal,” said Pandit Chanrochanakit, the deputy dean of the political science department at Chulalongkorn University in Bangkok.
Before the elections, diplomats in Bangkok warned that any delay in announcing the results might raise concerns, especially since relatively few independent election observers had been deployed.
Mr. Pandit said that hundreds of students organized by a scholars’ alliance had fanned out across the country to observe in 350 constituencies and had reported numerous irregularities, including vote counting that was not conducted transparently.
“Based on our observation, there are some problems that make this election not free or fair,” he said.
The number of invalidated ballots was nearly 6 percent, the Election Commission said, and 1.5 percent of ballots recorded no vote at all.
Sudarat Keyuraphan, Pheu Thai’s candidate for prime minister, urged normal politics to prevail.
“No matter the outcome, whichever party obtains the majority vote should get to form a coalition government first,” she said. “We don’t want to fight with anyone for power.”
The official results from Sunday’s election might not be released until early May.
Anti-junta forces are composed of both working-class people loyal to Mr. Thaksin’s populist party and an urban elite tired of the way in which politics have been polarized for nearly two decades.
Future Forward, a new party founded by Thanathorn Juangroongruangkit, an heir to an auto parts fortune, won a surprising number of seats in the partial count of Sunday’s elections, a remarkable feat for a party that didn’t exist a year ago. Mr. Thanathorn, one of the junta’s staunchest critics, has called for the nation’s military budget to be slashed.
“I have my own voice now, and I want a new voice to fix the country and bring the country into a better direction with a better economy,” said Panita Dispueng, a university student and first-time voter.
Much remains unknown about how politics will unfold in the coming months, especially since the military-drafted Constitution has introduced timelines and arcane regulations unfamiliar in Thailand.
If Mr. Prayuth continues as prime minister, he will not enjoy the same luxuries as when Thailand was ruled by a junta, analysts said.
“He will no longer have absolute power, and dealing with parliamentary politics is something that he is not familiar with,” Mr. Purawich said.
In the meantime, some of the pro-democracy parties are facing potential existential crises. Pheu Thai could be dissolved if outstanding complaints against the party move forward. Two of Pheu Thai’s precursors were dissolved for electoral fraud.
Mr. Thaksin is now in overseas exile after corruption-linked convictions, as is his sister, Yingluck Shinawatra, another former prime minister.
“The last gift that God can give you is hope,” Mr. Thaksin told his supporters on Monday, having predicted a much better showing by Pheu Thai.
Other parties, including Future Forward, have criminal cases against their executives hanging over them. Mr. Thanathorn could find out as early as Tuesday whether he will face jail time for a computer crimes charge that stemmed from a Facebook Live video he gave last year.
Human rights groups say the charge, which his deputy also faces, is politically motivated.