The number of candidates vying for Senate seats is far fewer than the Election Commission (EC) anticipated and many of them will progress through the first round of selection unopposed.
EC secretary-general Jarungvith Phumma said 7,210 people have applied to compete in the contest and the turnout is much lower than the EC expected.
According to the EC chief, the poll agency had expected at least 30,000 candidates.
Of the total, 6,705 are standing as independent candidates and 505 are fielded by the various associations. The agriculture and fisheries group has 1,397 candidates followed by the education and health group (1,043) and women, elderly and ethnic groups (821).
The intra-group voting will occur at three levels: district, provincial and finally national level on Jan 2.
The candidates can stand as independents or be fielded by registered organisations and must choose one of 10 social and professional groups to which they belong.
Pol Col Jarungvith said the low number of candidates means that several candidates will win the first round of selection, which will take place at the district level on Dec 16, by default.
Chartchai Na Chiangmai, a member of the Constitution Drafting Committee, said the low turnout could be because the candidates are not sure if they will eventually be picked by the regime.
He said the intra-voting will produce a shortlist 200 candidates from which 50 will be selected by the National Council for Peace and Order (NCPO) to join the 200 others it will select to create the 250-member assembly.
The Royal Thai Police (RTP), meanwhile, has opened a centre to step up security across the country during the Senate selection.
Deputy national police chief Pol Gen Srivara Ransibrahmanakul, commanding the operations, said that officers will be taught about election-related laws at a meeting on Friday.