
Kuthep Saikrachang said the PPP executives' meeting chaired by Prime Minister Samak Sundaravej, as party leader, agreed to nominate Chai for the House approval, expected to be held next week.
The executives reportedly preferred Chai to the other candidate Somsak Kiatsuranont because of his seniority and greater experience as a House member.
The seat of House speaker had been vacant since Yongyuth Tiyapairat resigned from the post last week.
Kuthep believed all coalition MPs would endorse Chai at the party's meeting next Tuesday.
Chai is father of Newin Chidchob, a close aide to former premier Thaksin Shinawatra. He was allegedly involved in a land scandal in his hometown of Buri Ram. Police are still investigating the case.
Before the meeting, Chai insisted he would not upset the party if he was appointed to do a new job.
Asked if he could become the next House Speaker, Chai said he could do any assignment the party gave him.
"There is no rift among the party's leaders," Chai said. "I'm just a party member. I will do my best in any role they want me to take."
The executives' meeting at 4.30pm was held after an urgent call from Prime Minister Samak Sundaravej in the morning. He reportedly wanted to ease the situation in the wake of his party's infighting over the nomination of the House speaker.
"Samak notified every party executive to attend in order to finalise the decision on who should be the House Speaker," PPP party executive and MP Nisit Sithuprai said.
Democrat MP Sathit Wongnongtoey said his party had picked a candidate to compete with that of PPP before the House votes next week, but would not reveal the name until the rival party named its candidate.