Prime Minister Prayut Chan-o-cha has insisted that he told US President Donald Trump that he would announce the election date late next year, not that the election will be held next year.
His confirmation has sparked criticism that his roadmap contradicts the Thai-US joint statement issued earlier.
Gen Prayut took a few minutes of his televised programme on Friday night to clarify his remark made during his visit to the United States about the political roadmap and a general election.
He said he assured Mr Trump during his visit the Thai government was adhering to the roadmap to democracy and there would be elections next year.
"President Trump didn't ask me about the issue, but I was able to assure him of the current administration's commitment to the roadmap, informing him that there will be elections by the end of next year, but by that I mean an election date would be announced late next year," he said.
"From then, the election will be held 150 days following the announcement," Gen Prayut said.
His remark implied the election would take place in 2019, later than previously indicated.
The prime minister told a group of Thais in Washington, DC earlier that the organic laws needed for a general election would likely not be enacted until November 2018.
Gen Prayut came under heavy criticism for causing confusion about when the national polls would take place. His timetable did not correspond to what the critics believed.
According to the 2017 constitution, elections must be held within 150 days, or five months, of the organic laws being passed. Those laws are expected to be completed within eight months of the promulgation of the charter.
While Gen Prayut stressed that only an election date would be announced next year, critics cited a joint statement between Thailand and the US issued after the meeting of the two leaders to claim Gen Prayut promised the polls would be held next year.
Pheu Thai's former energy minister Pichai Naripthaphan yesterday called on the government to clarify Item 8 on the US-Thai joint statement released on Oct 2.
Item 8 reads: "Recognising Thailand's strategic importance to the United States and the region, President Trump welcomed Thailand's commitment to the roadmap, which, upon completion of relevant organic laws as stipulated by the constitution, will lead to free and fair elections in 2018. The two leaders also recognised the importance of protecting and promoting human rights and fundamental freedoms."
Mr Pichai said the Foreign Ministry should review the conversation between the two leaders and inform the US if there is a misunderstanding about the issue and set the record straight.
He said the government's flip-flop on the election would further erode the international community's confidence in the country.
Former Democrat MP Charoen Khanthawong yesterday urged the prime minister to commit to the current roadmap that would see the election take place next year.
If elections were to be postponed for whatever reason, the government should let the public see for themselves what contributed to the delay, said Mr Charoen.
"The people want to see elections because they don't think the government is doing enough to address the problems. If things don't pan out as said, the people will be disappointed. I don't want his popularity to slide," said Mr Charoen.
Meanwhile, Gen Prayut, during the televised programme, rejected criticism that his visit was to negotiate weapon purchases with the US, saying state procurement plans must undergo due process.