Pheu Thai maverick Chalerm Ubumrung on Wednesday did not hold back in his attack against the National Council for Peace and Order (NCPO), one day after the regime lifted the prohibitions on political activities.
Mr Chalerm, who earlier this month was appointed to lead Pheu Thai's election campaign, zeroed in on the 2017 constitution and the 20-year national strategy, saying they were "bad legacies" of the current regime.
Mr Chalerm, however, pointed out that he was not talking on behalf of Pheu Thai.
On Tuesday, Prime Minister Prayut Chan-o-cha, in his capacity as NCPO chief, issued Order No.22/2018, lifting the prohibitions on political activities.
The lifting of the ban came as the organic law governing the election of MPs, which was earlier published in the Royal Gazette, came into effect on Tuesday.
Mr Chalerm said the charter, written by a panel chaired by legal expert Meechai Ruchupan, is a "shame", as it is modelled on the 1979 charter.
He pointed out that Section 272, which allows the Senate to take part in voting for the prime minister, will have to be amended.
Mr Chalerm also dismissed the regime's 20-year national strategic plan as "nonsensical" and added it should be scrapped, as it stopped short of addressing the issue of narcotics.
The Pheu Thai politician also lashed out at the controversial design of the ballot paper for the general election, in which the logos and names of political parties could be omitted.
According to him, those who came up with the idea have "twisted minds".
Without naming names, the former MP for Bangkok accused two agencies of collaborating to rig the election, and that he would set up a centre to monitor election campaigning and catch cheats.
He also lambasted the NCPO for being unclear on whether parties can carry out campaigns immediately after the ban on political activities is lifted.
It was reported that many parties are putting their campaigns on hold until a royal decree announcing the general election is published, as they worry about falling foul of the law.
Mr Chalerm said the pro-military Palang Pracharath Party will not be able to form a stable government despite the support of the 250-member Senate, and that the pro-democracy block -- which is comprised of the Pheu Thai, the Thai Raksa Chart, and the Future Forward parties -- would win at least 300 combined House seats.
When asked if Khunying Sudarat Keyurapan, who heads the party's strategic committee, was a suitable candidate for prime minister, he said if she was nominated by the party, he would lend his support. It has been widely reported that the two are not on friendly terms.
Meanwhile, Kanchana Silpa-archa, leader of the Chartthaipattana Party (CTP), on Wednesday joined the call to seek amendments to the constitution after the elections.
Ms Kanchana said that while the current constitution "is not all bad", it was only suitable for a period of time, and when a new government came to power, the document is likely to be reviewed.
The CTP leader said the 1997 charter was the best, because of its inclusive drafting process.
She also urged the EC not to omit party logos and names from the ballot paper.