The Move Forward Party (MFP) is expected to finalise its candidate for the House Speaker post in the middle of this month, said party secretary-general Chaithawat Tulathon.
He said the party has not decided who it will nominate, but the matter should be settled in this month when the Election Commission is expected to start endorsing poll winners.
Mr Chaithawat said the MFP and Pheu Thai, who are locking horns over the post, will solve the dispute within two weeks.
Pheu Thai leader Cholnan Srikaew said his party would not discuss who it will nominate for the House Speaker post until it reaches an agreement with the MFP.
"It was agreed at the recent meeting that the issue would not affect the coalition formation. This means if we have an agreement, the coalition formation will proceed without any conflict," Mr Cholnan said.
"We don't want any conditions. We don't want the issue to be settled in a free vote."
Khunying Sudarat Keyuraphan, leader of the Thai Sang Thai Party, on Thursday called on the MFP and Pheu Thai to sort out the issue instead of allowing a free vote over the selection of the House Speaker.
"A free vote will cause problems in the formation of the government. They should finalise it," she said.
Meanwhile, acting Democrat leader Jurin Laksanawisit said on Thursday it is an incorrect understanding that the House Speaker's role is to drive a political party's agenda.
Mr Jurin said the House Speaker must maintain neutrality during parliament meetings.
He added that the House Speaker's conduct is clearly governed by the constitution and parliamentary meeting rules.