* Erdogan wants to create strong executive presidency
* Cross-party panel tried but failed to agree on issue
* Erdogan's goal hinges on outcome of 2015 election
ISTANBUL, Oct 1 (Reuters) - President Tayyip Erdogan said on Wednesday forging a new constitution after a parliamentary election next year would be a priority for Turkey, signalling no let-up in his drive to create an executive presidency.
Erdogan, who became Turkey's first popularly-elected head of state in August after 12 years as prime minister, has made no secret of his ambition to change the constitution and bolster the powers of the presidency, a move opponents fear will herald an increasingly authoritarian rule.
"Immediately subsequent to the 2015 elections, all parties in the parliament should free themselves from prejudice and come together to write a new constitution based on reconciliation," Erdogan said in a speech at the opening of parliament.
"What will make the new Turkey stronger and provide a strong foundation for the country is a new constitution that corresponds with the new Turkey," he said.
A new constitution has long been one of Erdogan's key promises, meant to replace a text born of a 1980 coup which, despite numerous revisions, still bears the stamp of military tutelage.
A cross-party panel tried for two years to reconcile its differences on some of the most deeply divisive issues in modern Turkey, from the definition of citizenship to the protection of religious freedoms, but gave up last November.
Differences over proposals for an executive presidency were among the sticking points.
The outcome of next June's parliamentary election will be key to the fate of renewed efforts to write a new constitution.
If the ruling AK Party can control a two thirds majority, it could introduce reforms without opposition support, including the creation of the strong executive presidency Erdogan seeks.
The AK Party, which Erdogan founded in 2001, currently holds 313 of parliament's 550 seats, a strong majority but below the crucial two thirds threshold. (Writing by Ece Toksabay; Editing by Nick Tattersall and Gareth Jones)