The Senate has rejected two high-profile picks for the Constitutional Court -- one for supporting a lese majeste law amendment and the other for not being a preferred choice of the majority of senators.
Siripan Noksuan Sawasdi, a political scientist at Chulalongkorn University, and Chatri Atjananont, a former director-general of the Department of Consular Affairs, were voted down by the Senate.
Both fell short of securing half the Senate's support, or at least 100 votes, the minimum requirement.
Ms Siripan received an approval vote of 43 against 136, with seven abstentions and one no vote. Mr Chatri had 47 votes for, 115 against, 22 abstentions, and three did not register to vote.
They were nominated to replace outgoing Constitutional Court judges Nakharin Mektrairat, who is the court's president and Panya Udchanon.
The two candidates were chosen by a selection committee chaired by Supreme Court president Chanakarn Theeravechpolkul. The committee also includes House Speaker Wan Muhamad Noor Matha and opposition leader Natthaphong Ruengpanyawut.
The Senate began debating the qualifications of the two contenders at around 11pm on Tuesday.
Sen Nanthana Nanthawaropas maintained that the meeting should be suspended pending the Department of Special Investigation's probe into the alleged rigging of Senate elections.
She feared any choices of Constitutional Court judges approved by the Senate on Tuesday would be nullified later if and when the poll rigging case was found to have substance and a number of senators had to be subsequently disqualified. However, many other senators insisted the selection must go ahead, reasoning that the Senate risks dereliction of duty if it fails to conduct the vote.
The debate then proceeded, with many debaters, notably minority senators such as Angkana Neelapaijit, Ratchaneekorn Thongthip, and Dr Premsak Piayura, generally satisfied with both candidates' credentials.
At one point, the meeting was taken behind closed doors. Emerging from the closed-door session at 1.30pm, Senate Speaker Mongkol Surasajja called for a vote, which resulted in the candidates missing out on the posts.
It was reported the majority of "blue-affiliated" senators would refrain from picking both candidates. Blue is the colour of the Bhumjaithai Party.
Ms Siripan was criticised for signing up for a mass petition seeking to amend Section 112 of the Criminal Code, or the lese majeste law. In a letter to the Senate panel vetting qualifications of nominees, she explained she was merely exercising her right to voice her academic view.
She also responded to a Senate query on her stance on the imposition of strict ethical standards for political post holders, which has been blamed for Srettha Thavisin's dismissal as prime minister. The Constitutional Court dismissed him in August last year over an ethical violation related to the appointment of Pichit Chuenban as a minister.
Mr Chatri was not the "blue senator" choice of candidate from the outset. They reportedly favoured Sarawut Songsivilai, a former Highways Department chief, or Surachai Khan-arsa, a former governor of several provinces. Both did not make the cut in the selection process.