The Move Forward Party (MFP) and the Pheu Thai Party have agreed to have Prachachat Party leader Wan Muhammad Nor Matha as the House speaker, while MFP and Pheu Thai will each have one deputy's seat.
MFP leader Pita Limjaroenrat told a press conference on Monday night that both parties agreed on Mr Wan Muhammad Nor to be chosen as the House speaker on Tuesday. MFP would have the first deputy House speaker's seat and Pheu Thai the second deputy's.
He said that the six other coalition allies supported the decision. Prachachat is among the allies.
"This agreement is for unity among the eight political parties, who will do their best to nominate me as the prime minister," Mr Pita said.
He said the eight coalition allies would support him as their sole prime ministerial candidate.
He also said MFP and Pheu Thai would amend laws to pardon people prosecuted for expressing their political opinions and to reform laws concerning the armed forces, including those concerning martial law and internal security.
Pheu Thai deputy leader Phumtham Wechayachai said he proposed Mr Wan Muhammad Nor as the House speaker because the Prachachat leader was neutral and the proposal was a means for coalition allies to proceed with their government formation.
Pheu Thai leader Cholnan Srikaew said his party would not nominate any of its members to compete for the House speaker's seat, and other coalition parties would not have the right to nominate a Pheu Thai member for the job either.
Previously MFP actively promoted Phitsanulok MP Padipat Sunthiphada as its House speaker candidate. MFP and Pheu Thai failed to reach an agreement on the speaker's post on Sunday amid rumours Pheu Thai wanted its veteran member Suchart Tancharoen in the position.
In recent days Pheu Thai had stood firm that it deserved the speaker's seat because MFP already had the prime minister's position. Each party was to have 14 cabinet ministers.
Move Forward won 151 House seats in the May 14 general election while Pheu Thai had 141 seats.
Earlier on Monday, Mr Wan Muhammad Nor said he had not wanted the speaker's position but if his assumption of the post could ensure coalition allies' government formation, he would be willing to take it.