The Turkish opposition’s Good Party (IP) lost a founding member on Thursday after Ankara lawmaker Koray Aydın submitted his resignation.

"The Good Party was founded with great expectations and sacrifices. It managed to change a lot in Türkiye, but things began to go wrong in the past two years," Aydın said in a post on X.

He criticized the party for "wasting its energy on internal rivalries" by holding "untimely" congresses across provinces ahead of last year’s national elections.

He also argued the six-party opposition coalition IP helmed with the Republican People's Party (CHP) for the elections led to "a fault strategy" and went through a "disintegration period based on marginalization and injustice" after the presidential and parliamentary polls.

Aydın accused former Chairperson Meral Akşener of "ignoring" warnings from party ranks for "wrong rhetoric and erroneous decisions" during the campaigning period for the March 31 local elections, referring to Akşener’s insistence on competing alone in the municipal polls instead of allying with stronger parties.

Akşener’s move triggered a series of resignations earlier this year at Parliament’s fifth-largest party. More resignations followed even after she was replaced by Müsavat Dervişoğlu, a former member of the Nationalist Movement Party (MHP) like herself.

"After all these errors, the party council has failed to do a full and mature self-criticism," Aydın said. "The last five months prove there is no change at Good Party."

He said he would continue his duties as a lawmaker independently.

With Aydın’s exit, another former MHP member, IP’s seats at the 600-seat Parliament fall to 34.

The party had won only one provincial seat in the local polls.