The motion, which was signed by 127 MPs, alleged that Somsak had violated Article 125 and Article 143 of the Constitution while chairing the House meeting on Wednesday.
The motion was submitted to Senate Speaker Thiradej Meepian by Democrat deputy leader Thavorn Sennium and Rak Prathet Thai leader Chuwit Kamolvisit. The Senate speaker said he would proceed with the motion in line with the legal timeframe.
Thavorn alleged that Somsak failed to perform his duty as the head of the legislative branch without partisanship in line with Article 125.
Thavorn alleged that Somsak intentionally violated Article 125 by siding with the government.
He said Somsak also allegedly violated Article 143 by drawing his own conclusion that the four reconciliation bills were not related to financial affairs.
Somsak concluded during the House meeting on Wednesday that the four bills did not constitute laws related to the government’s budget so the House could deliberate them without requiring the prime minister to endorse them first.
Thavorn pointed out that the reconciliation bills would actually affect the government’s budget as the state might have to return Bt46 billion seized from former prime minister Thaksin Shinawatra.
Thavorn said Somsak’s behaviour had caused the opposition MPs to run out of patience and decide to seek Somsak’s impeachment.
The Senate speaker will have to verify the signatures of the MPs and send the case to the National Anti-Corruption Commission to investigate.
If the NACC finds ground to suspect Somsak’s wrongdoing, it will inform the Senate to consider impeaching him.