By Daren Butler
ISTANBUL (Reuters) - Turkish Prime Minister Tayyip Erdogan said in published remarks on Friday he was losing hope of building cross-party support for reforms that could see him installed in a newly empowered presidency but was determined to push the plans forward.
Erdogan has dominated Turkish politics since his Islamist-rooted AK Party swept to power in 2001, trouncing the opposition in three elections, delivering unprecedented economic growth and bringing a staunchly secular military to heel.
But under party rules he can't run for prime minister again when his term ends in 2015 and it is an open secret he wants to switch to a presidential system and become head of state.
Four political parties sit on a parliamentary commission set up after last year's general election to forge a new constitution and Erdogan has advocated the introduction of an executive presidency as part of the reform process.
Asked how work on the draft was going, Erdogan was quoted by Sabah newspaper as saying: "To be honest, my hope is diminishing with each passing day. Despite that, I think it is necessary to maintain the process in a decisive and resolute way."
Erdogan vowed at his AK Party congress last month to forge a constitution that would boost political freedom and democracy to replace the current one, which was drawn up after a military coup three decades ago.
He invited opposition parties for further consultations, but opponents fear the replacement of the current parliamentary system - a probable outcome of the constitutional review - would hand too much power to a man whose intolerance of dissent is viewed with increasing concern in Turkey and abroad.
Hundreds of activists, lawyers, politicians, military officers and journalists are being held on charges of plotting against the government or supporting outlawed Kurdish militants.
The U.N. Human Rights Committee said on Thursday Turkey was using a vague counter-terrorism law to hold many for long pre-trial periods without access to a lawyer and that some of its provisions flouted international law.
Erdogan has reminded his critics that the aim of the new constitution is to bolster, not diminish, political freedom.
"There can be no walking away from the table. Our position on a new constitution is clear. What is important here is to achieve the maximum common ground," he was quoted as telling reporters on his plane returning from Berlin.
"Of course there is no obligation for the four parties to come together. If the CHP comes, we will do it with the CHP. If the MHP comes we will do it with them," he said, referring to the two main opposition parties.
Erdogan's presidential ambitions face several obstacles.
A survey by Turkish pollster MetroPOLL in September showed Turks would prefer incumbent Abdullah Gul as their next president.
The two men, who co-founded the AK Party in 2001 but could in theory face each other at the next presidential election, have had increasingly public differences, trading barbed remarks this week over the police handling of a banned protest march.
The suggestion that Gul urged tolerance in policing Monday's protests, in which police eventually fired teargas and water cannon to disperse secularist demonstrators, led Erdogan to say the country did not need "double-headed government".
Gul responded by saying the division of responsibilities was clear under the constitution.
The two men have agreed to disagree in the past on issues including freedom of expression, and officials in Ankara say their relationship is built on deep mutual respect. Erdogan has repeatedly sought to play down any talk of a rift.
"We are saying the same thing ... Those who are trying to put the AK Party in a difficult position, they can't set the president and the prime minister against each other," he said at a news conference late on Thursday.
Erdogan is expected to announce whether he will press ahead with plans to hold early local elections next year at an AK party meeting on Sunday, a move seen as allowing him more time in a crowded election timetable to prepare a presidential bid.
Gul sent the proposed constitutional amendment, which would bring the local vote forward by five months, back to parliament after it failed to win enough support in a first reading.
Erdogan can either try to push the bill through the assembly again or abandon the plan, which would be a blow to his election preparations.
(Writing by Daren Butler; Editing by Nick Tattersall and Andrew Osborn)