Buoyed by the easy passage of its infrastructure financing bill, Pheu Thai hopes to carry the momentum into Parliament on Monday when senators and MPs begin their debate on constitutional amendments.
Deputy party spokesman Anusorn Iamsa-ard on Saturday said he expected attempts to amend the constitution section by section to sail through the joint session.
He was speaking after the governing party scored a victory on Friday night on the 2-trillion-baht borrowing bill, which was approved on first reading with a comfortable margin of 284 votes to 152.
Direk Thuengfang, a main sponsor of the charter changes, said he foresaw no obstacles to convincing lawmakers to support them, adding that he expected no tension in Parliament over the three days of debate.
Changing the charter section by section showed a political compromise, he said.
Even some people who do not sympathise with Pheu Thai view the 2007 charter as undemocratic because it was written by people selected by the coup-makers who overthrew Thaksin Shinawatra in 2006.
However, it has become clear that attempts to scrap the 2007 document and draft a brand-new constitution could lead to a new round of bitter political and social conflict.
Thaksin himself favours attempts to amend the charter piece by piece instead of rewriting it entirely, which he once said could threaten the survival of Prime Minister Yingluck Shinawatra and her government.
He ordered Pheu Thai MPs via Skype last Tuesday to discipline themselves to push through the megaproject spending bill and charter changes. The vote for the first reading of the charter changes is expected at the end of the debate on Wednesday.
Keys issues are Section 68 which bans political parties and party executives in cases where any are found to have committed election fraud, and sections related to the appointment of senators. Supporters of the changes will push for the end of the bans, and for all senators to be elected by the public.
Democrat spokesman Chavanond Intarakomalyasut said lawmakers had the right to seek approval to alter sections of the charter, but added that the opposition party saw the move as unnecessary as it would yield no benefits to the public.
He suspected a hidden agenda as the debate could take a detour to the controversial Section 291, now pending in Parliament. The section would contain provisions for the formation of a panel to write a new constitution if it is amended.
In any case, appointed senators are also expected to put up stiff opposition to any changes affecting them.
Prasan Marukpitak, an appointed senator, said on Thursday that the so-called Group of 40 would put up a fight against any changes, as it was an attempt by the ruling party to control the Senate after successfully dominating the Lower House.
But Mr Direk argued on Saturday that elections are part of the democratic process. This point would be emphasised in the forthcoming debate when it comes to the issue of abolishing appointed senators, he said.