At least 100,000 people are expected to seek election to the Senate in a process dubbed by the national poll body as the most complex in the world.
Election Commission (EC) chairman Itthiporn Boonpracong, said the election to pick 200 Upper House members from a range of professional groups, is expected to attract at least 100,000 applicants.
Unlike a similar contest which took place in 2018 when 10 professional groups elected representatives to form part of the current Senate, the upcoming election, to be held on May 11, will involve choosing members from 20 professional groups to fill the entire Senate.
The EC has invited qualified individuals to run for a Senate seat.
Candidacy applications will start 15 days after a royal decree is issued to hold a Senate election. Candidacy registration will be launched five to seven days after that.
Once registration ends, the intra-group election will be scheduled within 20 days.
Mr Itthiporn said the results may be known by July.
"We predict that no fewer than 100,000 will vie for places in the Senate," the EC chairman said.
The election will be at two levels -- districts and provinces.
Three successful applicants will make the cut in each professional group in each district, or 60 across 20 groups in a district. When multiplied by 928 districts nationwide, there will be 55,680 district-level applicants who will enter the provincial race.
A provincial, intra-professional group election will follow that will shortlist the applicants to two per group or 40 across 20 groups in each province, or 3,080 applicants across 78 provinces nationwide.
At the national level, the 3,080 applicants will go into an inter-group election. Ten applicants with the highest number of votes in each group or 200 across 20 groups will become senators.
He reiterated the need to impose a ban on senators being affiliated with political parties, saying the law intends to keep the Senate, to be at least indirectly elected by the people, impartial.
He warned of swift punishments against applicants and parties violating the ban.
Poll commissioner Pakorn Mahannop admitted background checks on two issues -- whether the applicant owns shares in media business or have criminal records, which bar them from contesting the election -- would be tedious.
The EC will be pressed for time as it only has up to seven days to check on media share ownership and up to five days to check for a criminal record.
"Imagine the workload associated with running checks on 100,000 people," he said.
EC secretary-general Sawang Boonmee, meanwhile, called the Senate election "the most complex" contest of its kind in the world.
He urged media outlets to produce an infographic illustration to help educate voters about the system.