Prime Minister Prayut Chan-o-cha will explain the issue regarding his incomplete oath-taking in the House of Representatives, Deputy Prime Minister Wissanu Krea-ngam said on Sunday.
If he is not busy, Gen Prayut, as the government leader, will answer questions on the issue in the House, though the prime minister may not talk for too long on the subject.
"He may speak only in a few sentences, and let others answer the question on his behalf," Mr Wissanu said.
Mr Wissanu insisted Gen Prayut was not attempting to evade House sessions and avoid explaining the matter, and said the prime minister cannot attend the House sessions if public engagements keep him busy.
Mr Wissanu also cited the example of fugitive ex-premier Yingluck Shinawatra, who assigned others to answer questions in the House on her behalf when she was prime minister.
Khunying Sudarat Keyuraphan, the Pheu Thai Party's chief strategist, said the opposition's motion to grill the prime minister was well-meaning.
The opposition has been concerned the government and its recently approved projects could be invalidated if the Constitutional Court rules that the incomplete oath-taking is unconstitutional.
The opposition has no malicious intentions against the prime minister and the issue should be discussed in parliament to find a proper solution, according to Khunying Sudarat.
Earlier, activist Srisuwan Janya asked the Office of the Ombudsman to forward the oath-taking issue to the Constitutional Court or the Administrative Court for a ruling on the government's legitimacy.
House Speaker Chuan Leekpai said on Friday a parliamentary debate on Gen Prayut's incomplete oath-taking will likely take place this month.
Mr Chuan said he would ask the secretariat of the House to inform the prime minister of the motion, adding Gen Prayut should clarify the reasons if for some reason he is unable to attend the debate.
Mr Chuan made the comments after accepting a motion for the debate filed by the seven-party opposition.
The motion was signed by 214 opposition MPs and lodged under Section 152 of the constitution.
The section allows the House to question and make proposals to cabinet ministers, without taking a vote.
Gen Prayut is accused of failing to recite the final sentence of Section 161 of the constitution, which requires the oath-taker to uphold and abide by the constitution, during the cabinet swearing-in ceremony last month.
He has so far twice failed to answer opposition questions on the issue in the House.