Thailand's Move Forward Party emerges as major winner in parliamentary vote
Around 52 million people were eligible to elect members of the 500-member lower House.
Thailand's two new emerging parties are well ahead with nearly all ballots counted, Election Commission data showed, delivering a heavy defeat to the army-backed government of Prime Minister Prayut Chan-ocha
With 97 percent of polling stations counted, the progressive Move Forward Party (MFP) had 13.5 million ballots in the popular vote, ahead of rival outfit Pheu Thai on 10.3 million.
Meanwhile, the United Thai Nation party of Prayut is far behind at 4.5 million.
"It is now clear that Move Forward Party has received overwhelming support from the people around the country," Pita Limjaroenrat, the Harvard-educated leader of MFP said on Twitter.
MFP will seek talks with Pheu Thai and a coalition deal is "definitely on the cards", the 42-year-old Pita told reporters in a separate statement.
Pheu Thai leader Paetongtarn Shinawatra congratulated MFP on their success and said "we can work together".
"We are ready to talk to Move Forward, but we are waiting for the official result," she said.
The Election Commission is not expected to officially confirm the final number of seats won by each party for several weeks.
But early on Monday in Thailand, it forecast MFP to win 113 out of a total of 400 constituency seats, just ahead of Pheu Thai on 112. A further 100 seats will be allocated to parties on a proportional basis.
The result is a heavy blow for Pheu Thai, the latest iteration of the political movement founded by Paetongtarn's father, billionaire former premier Thaksin Shinawatra.
Before this, Thaksin-linked parties had won most seats at every election since 2001 and Paetongtarn had urged voters to deliver them a landslide to see off the threat of military interference.
Despite their success, MFP and Pheu Thai may still face a battle to secure power thanks to the junta-scripted 2017 constitution.
The new premier will be chosen jointly by the 500 elected MPs and 250 senate members appointed by Prayut's junta - stacking the deck in the army's favour.
Adding to the uncertainty, rumours are already swirling that MFP could be dissolved by court order - the same fate that befell its predecessor Future Forward Party after it performed unexpectedly well at the 2019 poll.
Voters in Thailand were heading to the polls on Sunday in an election touted as a pivotal chance for change, eight years after incumbent Prime Minister Prayuth Chan-ocha first came to power in a 2014 coup. (Wason Wanichakorn/AP)