Thailand's King Maha Vajiralongkorn was due to inaugurate the opening of parliament on Monday, setting the stage for an attempt by the progressive Move Forward Party to form a government after its surprise election win six weeks ago.
Move Forward won big support from youth voters and the capital Bangkok, campaigning overwhelmingly on social media on an anti-establishment platform that could complicate its effort to win enough support to form a coalition government.
It will team up in parliament with the populist heavyweight Pheu Thai Party after the two won the lion's share of the house seats, trouncing parties allied with a royalist military that has controlled government since a 2014 coup.
But underscoring the challenge ahead, just hours away from parliament convening, Pheu Thai and Move Forward were still at loggerheads over who gets the position of house speaker, a pivotal post that could determine the passage of flagship legislation and timing of key votes.
They are part of an eight-party alliance and have played down talk of a rift over the speaker post, which must be decided in the coming days.
"Pheu Thai has a concluded on the matter and choosing the house speaker tomorrow has a definite direction. We will not let the public down," Pheu Thai lawmakers Suthin Klangsaeng told reporters.
Once chosen, the speaker must table a joint session of parliament to decide on a prime minister, which requires the votes of more half of the 750 members of the bicameral legislature.
The alliance is backing Move Forward leader Pita Limjaroenrat, 42, to become premier. The alliance has 312 seats and Pita needs 376 votes to secure the post.
He will need 64 more votes from either rival parties or members of a conservative-learning Senate that was appointed under military and has previously locked horns with Move Forward over some of its policies.
Pita last week said he had secured enough support in the Senate.
