United Thai Nation (UTN) Party leader Pirapan Salirathavibhaga has questioned the authorship of the tell-all "Prawit letter" and said it would not have repercussions on Prime Minister Prayut Chan-o-cha's political work.
Speaking after the release of the letter via social media on Friday, Mr Pirapan downplayed concerns the letter might undermine Gen Prayut's credibility and hurt his chances at the next poll.
"There will no impact on Gen Prayut.
"Personally, I believe (Deputy Prime Minister Gen Prawit Wongsuwon) didn't write the letter himself," the UTN leader said.
Gen Prayut took up membership of the UTN last Monday and is poised to seek re-election as prime minister by parliament on the party's ticket after the general election on May 7.
Gen Prawit, meanwhile, has turned to social media to speak his mind, saying the ruling party was set up because Gen Prayut Chan-o-cha expressed his desire to work in politics.
Gen Prawit said in the open letter posted on his Facebook page Friday that people were fully aware there was a major political change after the National Council for Peace and Order (NCPO) staged a coup on May 22, 2014.
The letter said that after the constitution was drafted and the country was gearing up for a general election in 2014, Gen Prayut expressed his desire to work in politics by claiming that he wanted to continue his mission and achieve it.
The letter said Gen Prawit established the Palang Pracharath Party (PPRP) to contest the election and nominated Gen Prayut as the party's prime ministerial candidate as he wished.
A source in the PPRP said that for Gen Prawit to write in a way interpreted as negative to Gen Prayut, with whom he has held close fraternal ties going back to their early military days, was not believable.
The source said the letter was likely to be the work of new members of the PPRP who are critical of Gen Prayut and were out to discredit him.
The letter was "fiercely opposed" by Gen Prawit's advisers prior to its release on social media. The advisers contended that it was ungentlemanly and that being hostile to one another goes against the long-cherished values of soldiers. However, Gen Prawit did not object to the letter being made public.
Core figures of the PPRP were competing to drive political campaigns ahead of the next election, the source added.