By Orhan Coskun and Nick Tattersall
ANKARA (Reuters) - Turkey will not hold a referendum on the powerful presidency sought by Tayyip Erdogan at least until the end of the year and could wait until 2019 if there is not enough support in parliament, the official overseeing the plans said.
Erdogan and the ruling AK Party he founded want to replace Turkey's parliamentary democracy with an executive presidency, a Turkish take on the system in the United States or France.
His supporters see such change as a guarantee against the fragile coalition governments that hampered Turkey's development in the 1990s. Opponents see it as a vehicle for his own ambition and fear growing authoritarianism.
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Investors are nervous that efforts to enact the change could plunge Turkey into its third parliamentary election in a little over a year if the AKP tries to extend its majority and secure the seats it would need to hold a referendum.
But Mustafa Sentop, a senior AKP official who heads a parliamentary commission on constitutional change, told Reuters there were no such plans and that, if necessary, the changes could wait until after the next election in 2019.
"We see the new constitution as a historical imperative for Turkey. If it is not done now, it will be at the top of the agenda for the next elections," he said in an interview.
"Frankly, we are writing a new constitution, not amending this one, so this proposal needs to be voted on by the people, via a referendum," he told Reuters.
A senior official in Erdogan's office also said the referendum could wait until 2019 if necessary, acknowledging that it was not a certainty that the AKP could win enough opposition support for a national vote before then.
The AKP has 317 lawmakers in the 550-seat assembly and needs at least 330 votes to call a referendum. Opposition parties agree on the need to replace the current constitution, born of a 1980 coup and still bearing the stamp of its military authors, but do not back the presidential system envisaged by Erdogan.
Sentop said he was confident the AKP could persuade enough opposition MPs to back a referendum and that, if so, it could be held in November, December or early next spring. A draft proposal for the new constitution was almost ready and would be put to parliament in October after its summer recess, he said.
Parliament speaker Ismail Kahraman sparked controversy in April by saying that the overwhelmingly Muslim country needed a religious constitution, a proposal at odds with the modern republic's founding principles.
His comments drew opposition condemnation and prompted a brief street protest, highlighting the schism in Turkish society reaching back to the 1920s when Mustafa Kemal Ataturk forged a secular republic and banished Islam from public life.
"Our proposal for the new constitution contains the concept of secularism and we don't have any problems with it," Sentop said, but added the text would also enshrine freedoms on religious worship and education.
Erdogan and the AKP have tried to restore the role of religion in public life. They have expanded religious education and allowed the head scarf, once banned from state offices, to be worn in colleges and parliament.
(Additional reporting by Can Sezer in Istanbul; Writing by Nick Tattersall; Editing by Catherine Evans)