Republican People's Party (CHP) Deputy Öztürk Yılmaz has criticized the lack of democracy within the party.
He called upon party officials to take responsibility for poor the results in the June 24 presidential and parliamentary elections.
Speaking at a press conference at Parliament, Yılmaz said: "We, as opposition, were defeated in the general elections. It necessitates self-questioning and self-criticism. Those who made mistakes should abandon their posts."
The CHP suffered some poor results in the June 24 parliamentary elections. It received only 22.6 percent of the votes, much lower than previous elections. The party also fell behind its presidential candidate Muharrem İnce, who got about 30 percent of the votes.
With the latest elections, the CHP has suffered nine straight election defeats under current party Chairman Kemal Kılıçdaroğlu, who took the party helm in 2011.
The poor results also sparked intraparty debates as one group blamed Kılıçdaroğlu for the repeated failures and demanded his resignation.
After the election, the dissidents launched a petition on July 16, calling for an extraordinary convention to overhaul the party leadership. However, the dissidents could not convince enough delegates to sign the petition.
Yılmaz said he has been on the ground and listening to requests citizens' requests for a month now. "The CHP grassroots complain about the lack of intraparty democracy. It is not a party of posts but a party of ideals. We should stand at the right point. Otherwise, the CHP would lose its credibility. Our intention should not be defending party positions. We can only collect our nation's vote by listening to their requests," he said.
The CHP deputy from eastern Turkey's Ardahan also announced that he resigned from Parliament's Foreign Affairs Committee, claiming that the committee "has not served any purpose."
"I resign from my post in the Foreign Affairs Committee, which has not achieved any results," said Yılmaz, adding that he would continue to take a key interest Turkey's foreign affairs.
Turkey's former EU Minister Volkan Bozkır chairs the 26-member committee.
Following Yılmaz's resignation, the CHP will have to assign a new member to the committee.