NLA president Pornpetch Wichitcholchai said he issued the order in response to the National Anti-Corruption Commission’s recommendation that impeachment proceedings be launched.
NLA member Jetn Sirathranont said the NACC and the ex-senators would give their opening statements to the assembly on Wednesday.
A nine-member committee would be appointed to question both parties, he said.
He said the committee would question both parties in the first week then allow them to give closing statements. Three days after that, the NLA would call a vote on the matter.
If all the ex-senators do not make a closing statement, the NLA would call the vote on March 12 or 13.
Jetn said this impeachment proceedings was different to proceedings against former Parliament president Somsak Kiatsuranont and his deputy Nikom Wairatpanich, both of whom escaped impeachment last month.
He said the charges against the 38 politicians included voting on an issue they had a conflict of interest in and voting on the third reading on the charter amendment, whereas Somsak and Nikom were charged with chairing a House meeting that deprived others of the right to speak against the amendment.
Ex-senator Nonthaburi Direk Tungfang said his group would send four representatives to give opening statements.
He said they felt that the charges against them were less severe than the charges levelled against Somsak and Nikom and were confident they would escape impeachment.