Story highlights April referendum scrapped a rule that required presidents to cut ties with political parties

Returning as AKP chairman gives Erdogan control of Parliament's most powerful party

(CNN) Turkish President Recep Tayyip Erdogan has resumed his role as chairman of the ruling AKP party in the controversial leader's latest move to tighten his grip on power in the country.

Turkey voted for a rash of constitutional changes last month in a referendum that will strip powers from Parliament and give the president unprecedented authority.

Until the April vote, Turkish presidents were obliged to cut ties with their parties to show their neutrality.

But the constitutional changes scrapped that rule, and on Sunday, the Justice and Development Party (AKP) returned the reins to Erdogan in a extraordinary Congress in Ankara.

"I am grateful to you for considering me worthy of becoming the leader of the Justice and Development Party once again," he said.

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