* Current constitution born out of military coup
* Referendum seen on changes including executive presidency
* Kurdish support could be vital
* Risk of division in ruling party
By Nick Tattersall and Orhan Coskun
ANKARA, Feb 18 (Reuters) - Burhan Kuzu has a weighty responsibility: drafting a new constitution that could set Turkey on the path to democratic maturity or send it lurching towards greater authoritarianism.
Time is not on his side.
Kuzu heads a cross-party commission that has until April to reconcile its differences on replacing the current constitution, a text born out of a 1980 coup which, despite numerous revisions, still bears the stamp of military tutelage.
The sticking points are many. From the definition of Turkish citizenship to the protection of religious freedoms, the articles under review go to the heart of some of the most deeply divisive issues in modern Turkey.
"The number of subjects that have been agreed upon are very few ... and they have left the chronic issues, the most contentious issues, to the end," Kuzu told Reuters in his parliament office, under a portrait of a sternly gazing Kemal Ataturk, founder of the modern Turkish republic.
Biggest among them, a revision which could affect Turkey's political trajectory for decades: the creation of an executive presidency to replace its parliamentary system.
Prime Minister Tayyip Erdogan, arguably the most powerful Turkish leader since Ataturk, has made little secret of his ambition to run for president in polls due next year and to bring teeth to a post that is now largely ceremonial.
Should Kuzu's commission fail to reach agreement by April, Erdogan has said he may seek a referendum on his own ruling party's package of amendments, likely to be sugar-coated with progressive reforms to try to get an executive presidency past the public.
Opponents fear the proposed new system would hand too much power to a man whose intolerance of dissent is viewed with increasing concern in Turkey and abroad.
"The spirit of our constitution must be dominated by the understanding that the state is for the individual, not that the individual is for the state," Erdogan wrote in an article in the New Turkey magazine this month, citing 13th century Muslim mystic Sheikh Edebali as a source of inspiration.
His choice of muse was revealing.
"Let man flourish and the state will also flourish" is one of Edebali's most cited quotes, a marked contrast in spirit to the current constitution, drafted more to protect a powerful state apparatus than to enshrine individual rights.
The words are held to be from Edebali's advice to Osman Ghazi, founder of the Ottoman dynasty, which went on to reign for six centuries. Further evidence, say Erdogan's critics, that his ultimate aim is not just to bequeath Turkey a new constitution, but to install himself as a modern-day sultan.
"Erdogan wants a dictatorship," said Suyehl Batum, a constitutional expert from the main opposition Republic People's Party (CHP). "He wants a presidential system in which he retains power over his party and chooses his prime minister at will."
Barred from running for prime minister again, Erdogan has dominated politics since his Islamist-rooted AK Party came to office in 2002, presiding over Turkey's emergence as a power in the Middle East and over an unprecedented rise in prosperity.
He has muzzled a military that had ousted four governments since 1960, all but winning a battle with the old secular elite which emerged when Ataturk founded the modern republic on the World War One ruins of the Ottoman Empire.
But the transformation has come at a cost. Hundreds of military officers have been jailed on charges of plotting a coup against Erdogan, while others including academics, journalists and politicians face trial on similar accusations.
Ascending to an executive presidency would cement Erdogan's position as Turkey's most significant leader since Ataturk, but it will require astute political manoeuvring to win support from either Kurdish or nationalist opposition deputies.
"Erdogan's charisma is both an advantage and a liability. It's an advantage because he possesses powers of persuasion; it's a liability because of his over-confidence, his aversion to criticism," said Ihsan Yilmaz, professor of political science at Fatih University in Istanbul.
Constitutional amendments require two-thirds support in the 550-seat assembly, or 367 votes.
If Kuzu's commission fails to forge a bill - which looks likely, as it has agreed on just a third of around 85 articles discussed so far - Erdogan's AK Party, which controls 326 seats, would struggle to pass its own amendments unilaterally.
But with 330 votes Erdogan could win the 60 percent needed to win approval for a referendum.
"If the commission's work is inconclusive and there is no other way, then the AK Party will submit its own plan," said Mustafa Sentop, a deputy chairman of the ruling party and a member of Kuzu's commission.
"It would include our own proposals and it would include the presidential system. That is certain."
Erdogan appears to have been on a charm offensive in recent months, extolling the virtues of a presidential system and arguing it would end the current "two-headed" governance structure which he says stymies progress on reforms.
Cynics see fledgling peace talks with Abdullah Ocalan, the jailed leader of the Kurdistan Workers Party (PKK) rebel group, as part of a strategy to win Kurdish support for constitutional changes including an executive presidency.
The pro-Kurdish Peace and Democracy Party (BDP) has 26 deputies in parliament and its backing could be decisive.
"The BDP ... can help Erdogan take his further-empowered presidential model, injected in a draft constitution, to a referendum," political commentator Yavuz Baydar wrote in Today's Zaman newspaper this month.
"The critical question is whether Erdogan will attempt to take this path to his dreams," he said, noting strong sensitivities on the Kurdish issue among the AK Party's conservative grassroots supporters.
Such a "two-party consensus", as Baydar dubbed it, would risk isolating parts of the AK Party who would rather see incumbent President Abdullah Gul serve another term than see Erdogan tighten his grip on their party even further.
A survey by Turkish pollster MetroPOLL in September showed Turks too would prefer Gul as their next president.
"He risks fracturing his own party. There are already those who view him as increasingly authoritarian and are apprehensive. There are those who support Gul, and that includes the base of the party," said Fatih University's Yilmaz.
In a sign of the difficulties that may lie before him, Erdogan was forced to abandon an attempt last year to bring local elections, due in March 2014, forward by five months after failing to win enough parliamentary support.
An earlier date for local elections would have given him more time to prepare for the presidential contest in 2014.
Politicians from all the main parties agree that Turkey's constitution needs to be replaced. But Erdogan's insistence on an executive presidency could mean forcing through hurried changes that will harm rather than advance Turkish democracy.
"We have extreme centralisation already. This change will not suit Turkish political culture. It would be a terrifying situation," said Nazli Ilicak, a well-known conservative politician and long an outspoken supporter of Erdogan.
"In the U.S., you have much looser party structures, you have primaries and party congresses and processes to determine your candidate. We just don't have that culture here, it's not like that in Turkey," she said. (Additional reporting by Jonathon Burch in Ankara, Ayla Jean Yackley and Daren Butler in Istanbul; Writing by Nick Tattersall; Editing by Alistair Lyon)