The Office of the Ombudsman on Thursday forwarded a petition to the Constitution Court for it to rule on the validity of the Feb 2 general election.
The petition seeking to have the poll invalidated was lodged with the office by Kittipong Kamolthammawong, a law lecturer at Thammasat University.
Ombudsman office spokesman Raksakecha Chaechai will hold a press conference on Friday to discuss the matter.
In his petition, Mr Kittipong said elections could not be held in 28 provinces in the southern provinces which had no candidates on Feb 2.
If poll reruns are held in those provinces, he said this could breach the constitution which stipulates that a general election must be held on a single day nationwide.
Mr Kittipong also alleged that candidate registrations in some constituencies were unfair as some registration venues were changed without advance notice.
He also said the vote counts on the Feb 2 election day were already known and they would affect the decisions of voters in the poll reruns, which would raise questions of unfairness.
People's Democratic Reform Committee (PDRC) co-leader Thaworn Senneam said he will petition the charter court on Friday to rule on the government's caretaker status now 30 days have passed since the Feb 2 poll.
Meanwhile, election commissioner Somchai Srisuttiyakon said poll reruns in the three southern border provinces of Yala, Pattani and Narathiwat are likely to take place on March 30, the same day as the Senate election is held,
Mr Somchai, who is in charge of election management, said it is undecided whether poll reruns in two other provinces — Prachuap Khiri Khan and Satun — can be held on March 30, as the two provinces are still prone to possible disruptions.
The EC will hold a seminar in Songkhla's Hat Yai district on Friday to discuss the rerun of the Feb 2 general election and Jan 26 advance voting in 14 southern provinces with representatives of political parties, before deciding which provinces in the South the EC can hold poll reruns in, Mr Somchai said.
EC chairman Supachai Somcharoen said at least four political parties have agreed to send representatives to the seminar. He encouraged all concerned to share their views on how to ensure the reruns proceed smoothly.
Mr Supachai also urged the PDRC not to disrupt the seminar.
The EC chairman refused to comment on whether the Yingluck Shinawatra government's caretaker status has expired.
The government's critics argue the caretaker government can no longer remain in power under constitution rules because the Feb 2 poll was unsuccessful.
Mr Supachai said the issue should be left to politicians and academics to interpret. All the EC is required to do is to hold elections, he said.
He insisted that the EC's petition to the Constitution Court to decide whether the EC or the caretaker government has the authority to call poll reruns in 28 constituencies in eight southern provinces which had no candidates was not an attempt to derail the Feb 2 poll.
The eight southern provinces are Surat Thani, Krabi, Trang, Phatthalung, Songkhla, Chumphon, Phuket and Nakhon Si Thammarat.
The EC needs to be sure election reruns are held in line with the law to complete the Feb 2 poll so that no complaints to have the poll invalidated are lodged, Mr Supachai explained.
But it is up to the charter court to decide, and the EC will respect the court's ruling, Mr Supachai said.