Renu Tunkachivangoon tendered her resignation as a senator a day before the joint parliamentary session to vote for a new prime minister on Thursday.
Following Ms Renu's resignation, which took effect on Wednesday, there are now 249 appointed senators, reducing the number of parliamentarians to 749. This will make the number of votes for a prime minister required by the constitution to be 375 from the lower and upper chambers of the parliament.
Ms Renu served as a deputy secretary-general to the prime minister for political affairs before she was appointed to the Senate by the now-defunct National Council for Peace and Order.
The eight coalition parties, led by the Move Forward Party (MFP), command 312 MPs. MFP leader Pita Limjaroenrat, the party’s sole prime ministerial candidate, now needs 63 votes from either senators or MPs outside the bloc.
Senator Naowarat Pongpaiboon said on Thursday that he stood by his intention made during a parliament session that senators should not have the right to choose a prime minister. The national artist said he would abstain from voting for any candidate on Thursday.