Several politicians have voiced their disagreement with the Move Forward Party's plan to celebrate National Day on June 24 instead of Dec 5, with veteran politician Nipit Intarasombat calling the party out for disrespecting the monarchy.
Mr Nipit, a member of the Palang Pracharath Party who represented Phatthalung in parliament from 1992-2013, took to Facebook on Sunday to question the remarks made by MFP spokesman Rangsiman Rome on Saturday, the 91st anniversary of the 1932 revolution which established Thailand as a constitutional monarchy.
During Saturday's discussion at Thammasat University's Tha Phra Chan campus, Mr Rangsiman said the Future Forward Party, MFP's predecessor, had proposed to former parliament president Chuan Leekpai that June 24 become a national holiday, but the proposal was not realised.
The National Day of Thailand is celebrated on Dec 5 each year, which was the birthday of the late King Rama IX.
In the post, he said he was saddened by Mr Rangsiman's remark, saying it showed the MFP's lack of respect for the royal institution.
"Normally, countries with monarchs as their heads of state set their national day on the birthday of their monarch," Mr Nipit wrote, using the United Kingdom as an example.
As the MFP often refers to the UK as a model for democracy, Mr Nipit said he found it surprising that the party wants to celebrate National Day on the day when Thailand's monarch was deprived of power instead of the monarch's birthday.
Srettha Thavisin, a prime ministerial candidate of the Pheu Thai Party, wrote on his Twitter account that whether June 24 became a holiday or not does not matter.
What's important, he said, is that the people do not accept a coup or a dictatorship.
Pheu Thai and the MFP won the most seats in the May 14 election and have agreed to form the next coalition government with six other small parties.
Mongkolkit Susintharanong, former leader of the Thai Civilized Party, also took to Facebook to say he disagrees with the idea of changing the National Day from Dec 5 to June 24.