The Constitutional Court is expected to rule next month on whether to dissolve the Future Forward Party (FFP) over allegations it attempted to overthrow the constitutional monarchy.
Natthaporn Toprayoon, who petitioned the court early this year seeking disbandment of the FFP for violating Section 49 of the charter, said he expects a ruling by the middle of January.
His prediction came after the court rejected the FFP's request for a full inquiry into the case. The court said there was sufficient evidence to rule on the case without holding an inquiry under Section 58 (1) of the Constitutional Court's Procedure Act.
Mr Natthaporn cited the dissolution case against the Thai Raksa Chart Party (TRC) early this year, in which the court handed down its ruling without conducting an inquiry given there was already sufficient evidence.
He said the court may schedule the ruling date when it meets tomorrow.
In his petition, Mr Natthaporn accused the FFP, its leader Thanathorn Juangroongruangkit, party secretary-general Piyabutr Saengkanokkul and party executives of violating Section 49 of the charter which prohibits actions that undermine the constitutional monarchy.
He cited FFP actions including the party's regulations and also speeches and lectures made by the senior party figures.
FFP spokeswoman Pannika Wanich said on Monday the party was bracing itself for the court's ruling after the request for an inquiry was rejected.
"If the court ordered an inquiry, we would make preparations because witnesses and evidence would be called. But without an inquiry, we just have to be prepared for a ruling that we can't predict," she said.
Meanwhile, Metropolitan Police Bureau chief Pakkapong Pongpetra said police are seeking the parliament president's permission to summon three FFP lawmakers to answer charges in connection with the "flash mob" protest in central Bangkok earlier this month.
The three are Mr Piyabutr, Ms Pannika and party-list MP Pita Limjaroenrat, who face charges of violating the law on public assembly.
Pol Lt Gen Pakkapong said investigators have submitted a letter to the national police chief seeking the parliament president's permission to summons the FFP trio. MPs are protected by parliamentary immunity, meaning police are required to obtain the parliament president's permission to summon them to hear charges.
He said Mr Thanathorn and FFP member Pairatchote Chantarakhachorn have been summonsed to respond to the charges at Pathumwan police station on Friday.
The city police chief denied the charges were politically motivated and said the case was being handled based on evidence.