The decision was made at a meeting of the eight-party coalition on Monday at Thai Summit Tower in Bangkok, Pita revealed.
The 42-year-old candidate said that he would still run for the coalition, but added that if he did not see a "significant" improvement in support, he would be prepared to back Pheu Thai's nominee.
Clarifying the term “significant”, Pita said that he meant a gain of 10%, or around a total of 340–350 votes.
Just two days before the meeting on Monday, Pita had said that if his party failed to become the leader of the next coalition government, he would allow the second-largest partner, Pheu Thai, to take over as coalition leader and try to form a new government and would be ready to support its PM candidate.
Pita also clarified after hours of discussions that the decision to push for an amendment of Section 272, which allows the 250-member Senate to vote in the election of the prime minister, was solely an initiative of Move Forward and not the whole alliance.
Move Forward is making twin simultaneous attempts to have Pita elected as prime minister: one is to get the required 375 votes in the second round, and the other is to work towards amendment of Section 272 to make the Senate irrelevant in the PM election.
Pita clarified that proposing a candidate’s name once again in the second round of voting would not violate Parliamentary Rule No. 41, which forbids resubmitting a motion that has already failed once in the same session. He was responding to remarks by Senator Seree Suwanpanont, who had claimed that the Constitution prohibited proposing the same name again.
Pita argued that the barring of a motion from being submitted again and a candidate contesting again were not the same.
Pita also told reporters that he would not step back from his pledge to amend Article 112 on lese majeste, as it was a promise he had made to the people during the election campaign.
Pheu Thai deputy leader Phumtham Wechayachai said that he would give Move Forward the opportunity to do its best, but if it does not succeed the appropriate change would be needed.
Phumtham, however, added that there was no alternative candidate to Pita so far.
He had earlier said that Move Forward’s push to amend Section 272 was impractical, pointing to signs of disharmony in the coalition.