Anusorn Tamajai, chairman of the Democratic Heroes Foundation, said timely elections that were free and fair would help prevent political violence that could lead to military intervention.
He said there was no time to lose as the economy had suffered damage of more than 500 billion baht from the protracted protests.
A general election by August would also allow parliament to consider the budget for the next fiscal year.
The election could also be monitored by international organisations, he added.
The foundation also thought that between now and August, a referendum could be held to let voters decide if a people’s council should be established to map out a comprehensive package of national reforms, which could take up to three years to implement because of the complexities.
The referendum could also determine if the constitution should be amended.
Mr Anusorn said if the referendum decided in favour of a council being set up, it should comprise 490 members, 400 of them elected and the rest nominated by scholars and academics.
The economist said the proposed council differed from the idea put forward by the anti-government People’s Democratic Reform Committee. The PDRC has said it should have the power to nominate the council members.
The foundation, formed by activists from the Black May 1992 violence in which demonstrators were crushed in a military crackdown that left 52 dead, also wants reform of judicial institutions. It has organised a seminar entitled “From May 1992 to May 2010: How Many More Mays Does Thailand Need?” in Bangkok.
The period encompasses several episodes of political violence, including the 2010 crackdown on red shirt protesters.
Jaran Ditapichai, a veteran activist and a red-shirt leader, said it might be five years before the current deadlock could be resolved.
Siam University law lecturer Ekachai Chainuvat proposed revocation of Section 309, which allows for future coups and unconstitutional intervention in the national administration.
Red-shirt lawyer Saovalux Phongam said she would like the caretaker government to recognise the jurisdiction of the International Criminal Court to help mete out justice for political prisoners.