The conservative Bhumjaithai party is expected to win 198 of the 500 seats, according to a forecast from Thai media company Channel 3.
"Today's victory belongs to all Thais, regardless of whether you voted for us or not," says Anutin Charnvirakul at his election vigil.
The opposition party, the reformist People's Party, is projected to win 97 seats. Party leader Natthaphong Ruengpanyawut admits defeat.
"We stand by our principle of respecting the party that becomes the largest and its right to form a government," he says.
The former prime minister, convicted and imprisoned Thaksin Shinawatra, looks set to win 86 seats in parliament with his Pheu Thai party.
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