Selahattin Demirtaş, the former head of the Peoples’ Democratic Party (HDP), known for its alleged ties to the outlawed PKK terrorist group, announced Wednesday that he is retiring from active politics after criticizing his party over Türkiye’s landmark presidential and parliamentary elections on May 14.

"I quit active politics at this stage," Demirtaş wrote on Twitter from his jail cell in the western province of Edirne.

Demirtaş, who earlier ran as presidential candidate against President Recep Tayyip Erdoğan, has been in prison since 2016 for spreading terrorist propaganda and having ties to the PKK and risks up to 142 years in jail. However, he has still shared political opinions on social media since.

He also apologized for "failing to follow a policy worthy" of his people and pledged to work better to learn from criticism against him.

Demirtaş’s remarks come hours after he criticized the HDP for lack of an effective election strategy. In an article for an independent Turkish daily newspaper, Demirtaş bemoaned that the Kurdish political movement made "shoddy work" and "realized too late the fact that the latest elections were the most important in all aspects."

"I’ve been trying to spread this fact with my letters and messages in the past five years, but my voice resounds, and its echoes only come back to me," he wrote, eliciting backlash from the party’s base.

While managing to hold on to 61 parliamentary seats by running under the Green Left Party (YSP), the HDP saw its hopes dashed in presidential polls after endorsing the main six-party opposition bloc’s joint candidate Kemal Kılıçdaroğlu who was defeated by Erdoğan on Sunday’s runoff.

Erdoğan often lambasts Demirtaş as a "terrorist" for his part in inciting public riots in favor of the PKK across Türkiye’s southeast that left dozens dead in 2015 and says that his release is "not possible" as long as he is president.

Kılıçdaroğlu had promised to release Demirtaş, along with the PKK’s jailed ringleader Abdullah Öcalan, if he had been elected.