The opposition's petition calling for a definitive ruling on when Gen Prayut Chan-o-cha's eight-year premiership should end is expected to be forwarded to the Constitutional Court for a review on Monday.
The petition was lodged with parliament president Chuan Leekpai on Wednesday under Section 82 of the constitution, which states that Constitutional Court requests must be submitted via a parliament president.
The opposition believes Gen Prayut's eight-year tenure expires on Aug 24, as he has served two back-to-back four-year terms as prime minister since the 2014 coup.
Section 158 of the 2017 charter caps the term of a prime minister at eight years, regardless of whether those years are consecutive or not, to prevent him or her from staying in power too long.
Gen Prayut was installed as prime minister on Aug 24, 2014, a few months after the May coup of that year.
In early 2019, he was nominated as the prime ministerial candidate by the Palang Pracharath Party to compete in the election that year.
He was then endorsed by a joint sitting of MPs and senators following the general election in March.
Sukit Atthopakorn, an adviser to Mr Chuan, said the signatures of the 172 MPs in the petition have been verified, pending further submission to the court.
Mr Chuan has seven days to examine the petition from the day of its submission before forwarding it to the court, which is expected to consider whether to accept it or not.
The petition, which also asks the court to suspend Gen Prayut from duty while the ruling is pending, is expected to be filed with the court on Monday.
Deputy Prime Minister Wissanu Krea-ngam on Friday said Gen Prayut may assume the role of caretaker prime minister even if the court rules he has reached his term limit.
A prime minister is only not allowed to assume the caretaker role when he is instructed by the court against doing so, Mr Wissanu said.
"In other cases like a House dissolution, the prime minister can assume the caretaker role," he said. "Even if the court rules he has reached his term limit, he [may or may not assume the role]."
"[If not] the role will be assumed by Deputy Prime Minister Prawit Wongsuwon," Mr Wissanu said.
Gen Prayut on Friday declined to comment on the dispute over his term limit.