The decision was unanimously made at a party meeting on Tuesday.
The Pheu Thai-led coalition has been working hard to win more support from members of both Houses and even held cordial talks with Move Forward last Wednesday.
Move Forward secretary-general Chaithawat Tulathon told reporters that the party has decided not to vote for Srettha because it does not want to be linked with the formation of the new government.
“We consider the current endeavour to establish a government contrasts with the will of the people, which was exhibited by the result of the May 14 election,” he said.
Move Forward won the election with 151 MP seats.
Chaithawat said that voting for a candidate from an alliance led by Pheu Thai went against his party’s aim to “switch off” the power of junta-appointed senators. Instead, he said, it was more like accepting their desire to reject the election results.
In the first round of voting on July 13, just 13 senators voted for Move Forward leader Pita Limjaroenrat, who was the only PM candidate.
Chaithawat also said that the Pheu Thai-led coalition does not aim to forward any progressive policies that will truly benefit the people. He said this alliance respects all parties more than it respects the people, referring to Pheu Thai’s moves to tie up with members of the outgoing ruling coalition.
He added that the decision to not vote for Srettha was based on feedback from supporters.