Chaithawat Tulathon, the ex-leader of the now-defunct Move Forward Party, on Friday expressed disappointment after the House rejected the proposal to include lese majeste in the list of offences that would be pardoned under a new political amnesty bill.
Mr Chaithawat was banned from politics for 10 years but was invited by the opposition People's Party (PP) to serve on a special House committee studying the proposed amnesty bill.
The vote took place on Thursday, with 270 MPs voting against including the offence and 152 voting to support the proposal. The proposal was part of a House special committee report on the proposed amnesty bill.
While the House voted against including lese majeste, it endorsed the rest of the report, which outlined the results of the committee's research into various forms of amnesty that could be pursued.
Mr Chaithawat said the House's decision meant that the lese majeste issue would not be forwarded to the cabinet for consideration, although the proposal included suggestions that would help foster reconciliation.
The vote result also suggested that the government might not propose its own version of an amnesty bill, dampening hopes for measures or policies to resolve political divisiveness, he said.
The ruling Pheu Thai Party might not propose an amnesty bill before the current session ends on Oct 30, he said.
However, Mr Chaithawat said that he and the MPs from the main opposition PP hoped to see other versions of the amnesty proposal submitted to the House.
The PP advocates for amnesty for those convicted under Section 112 of the Criminal Code, also known as the lese majeste law, while MPs in the government coalition disagree.
The PP's amnesty bill is among four amnesty-related bills submitted to the House.
The three others were sponsored by civil groups: the United Thai Nation Party and the Khru Thai Party.
The proposed amnesty, as put forward by PP, would cover all politically motivated cases since Feb 11, 2006, the first protest held by the People's Alliance for Democracy (PAD) against the Thaksin Shinawatra administration until the day the bill takes effect.
United Thai Nation member Pongpol Yodmuangcharoen said there have been 57,966 cases involving political offences since 2005. Of these, 1,206 involve offences under Section 112, he said.