For 84 years, modern Turkey has been defined by a holy trinity - the army, the republic and its founder, Mustafa Kemal Ataturk. Each was linked inextricably to the others and all were beyond reproach. But a deep transformation is under way in this nation of 70 million and elections on Sunday may prove a watershed: Liberal Turks, once the principal political supporters of the nation's ruling elite secular, are turning their backs on it and pledging their votes to religious politicians as well as a new array of independents.

They say they are fed up with attempts by the elite to divide Turks on the basis of religion and that Turkey, a predominantly Muslim democracy with a rapidly growing economy, needs to relax its controlling approach toward its own citizens in order to become a modern democracy. "This election is a power struggle between those who want change and those who don't," said Zafer Uskul, a prominent constitutional lawyer and human rights advocate who is running with Prime Minister Recep Tayyip Erdogan's Islamic-inspired party in southern Turkey. "Religion is just an excuse."

"In 50 years, people will write that this was the time Turkey started to come to terms with its own people," added Suat Kiniklioglu, a foreign policy expert and one of about 20 liberal Turks who recently joined Erdogan's party as it tried to appeal to secular Turkish society. The real threat to Turkish democracy, Kiniklioglu and others argue, comes not from Islamic fundamentalism, but from political meddling by the military. Commanders have deposed elected governments four times in Turkey's history and threatened a fifth in April, precipitating elections.

Now, as the election approaches, unleashing a power struggle between the nation's secular elite and a group of religious politicians who draw their support from Turkey's lower and middle classes, a vocal new civil society may just tip the balance, and help offset the danger of rising nationalism. "You heat water to 99 degrees and it's still water," said Baskin Oran, a political science professor running as an independent candidate in Istanbul. "You heat it one more degree and it's not water anymore. This one degree is the year 2007."

The current shift has its roots in the dual nature of Turkish democracy. From its beginnings in the 1940s, a powerful chain of bureaucrats, judges and army generals from the secular upper classes have controlled the most sensitive affairs, while the elected government - now held by Erdogan's Justice and Development party - manages more mundane aspects, much like a municipality.

But society has changed dramatically in recent decades, with religious Turks gaining wealth and status and moving into public view. Women in head scarves - precisely those whom early Turkish legislation meant to ban from public buildings - are in shopping malls, on motor scooters and behind the wheels of cars. "This narrow shirt of secularism has become a little too tight and choking for Turkish society," said Volkan Aytar, of the Turkish Economic and Social Studies Foundation, a prominent think tank.

Ilhan Dogus, a member of the Young Civilians, an association that opposes the military's role in politics, said mischievously that women in head scarves are more likely than their secular counterparts to know that Marx refers to a German philosopher, not the British department store Marks and Spencer. The state elite "wanted society to fit their theory," said Recep Senturk, a research fellow at the Center for Islamic Studies in Istanbul. "If religion doesn't disappear, we'll make it disappear because our theory says so."

Liberals like Uskul are pioneers in joining political forces with Erdogan's party, known by its Turkish initials, AK, which many secular Turks consider to be too Islamic. In Tarsus, an upper-middle-class town in southern Turkey that has supported secular parties, Uskul, 63, was talking to lawyers Wednesday, asking for their vote.

"Some of you might be asking, 'What is he doing in the AK party?' " he said at the Tarsus Bar Association, peering earnestly through rimless glasses and clasping his hands humbly between his knees. "There was no other party to do what I wanted to do in Parliament. The people who should be defending democracy are holding on to military coups." A woman in a black T-shirt shot back: "I wonder whether you still have worries about AK as a threat to secularism." He replied: "My wife has no concerns. Nor does my daughter, and you shouldn't either."

The portion of Turkish society hanging onto the old order is shrinking, Aytar asserts, so when more than a million Turks gathered this spring to protest what they said was creeping Islamism, bizarre combinations were on display. People wore masks of Ataturk, who died more than 50 years ago. The music that played was from the 1930s. "They have calcified," Oran said. Oran estimates that parties representing that old order will get about a quarter of the vote, largely thanks to a campaign of fear that plays on secularism. An ad last week in Cumhuriyet, a staunchly pro-state daily, showed a black ballot box and a woman's eyes behind the rectangular cut-out, evoking a facial veil. "Are you aware of the danger?"

Before the presidential election this spring, a television ad flashed the years 1881 and 2007 on a black screen: The year of Ataturk's birth and the year his secular reforms died. The campaign was a final straw for Turkish liberals, why say that it distracts from Turkey's real problems: unemployment, insufficient social security, poor relations with Kurds, differences over the island of Cyprus. A dangerous offshoot is nationalists, who play on poorer Turks' fears by warning that the European Union wants to tear Turkey apart. The main nationalist party appears set to win enough votes to make it into Parliament, supported by poorer Turks, overwhelmed by the sharp changes in the country over the past five years.

Liberals have responded to the campaign with wit, appealing to everybody in Turkey's complex political landscape. When a liberal newspaper asked for a response to the ads, Ferhat Tumer, a 32-year-old advertising director, and his colleagues began to brainstorm. The result was a bubble-gum-colored two-minute cartoon in the style of a late-night American television ad that only two Turkish television channels were willing to air but that became a cult favorite overnight on the Internet. "Is thinking a crime? Speech not allowed? Is your society excluding you, or forcing you to take sides?" the salesman-style voiceover asks in staccato Turkish. "Move away from fragile systems that are easily toppled. Original Democracy, adhered to by millions around the world, is now available in Turkey!"

The short would probably not have been possible five years ago, although Tumer and three of his colleagues had first proposed a much more confrontational version that was a direct dig at the military. The newspaper, Radikal, although brave, was not foolhardy. "We believe there is a hidden group of people in Turkey who are bored by this talk," said Tumer, fiddling with a green yo-yo at a glass table. "We know you're not afraid of this scarf. When she takes it off, she still has the same ideas." "This paranoia, this tension, for the young generation, it's just old-fashioned," he said.

Dogus's group, the Young Civilians, made posters of a fictitious presidential candidate who combines all the qualities most despised by the elite: a Kurdish-Armenian woman in a head scarf. Inherent in Turkey's progress was a strange contradiction. The state excluded religion from public life, and looked down upon religious Turks as backward, yet when they became more integrated in public life, condemned them as enemies of the state.

"Secular urban forces headed by the army look at these people as if they were aliens from outer space," said Dogu Ergil, a sociology professor at Ankara University. "But they are the products of the very regime that left them out." As Turkey moves ahead, it will have to grapple with where Islam fits in the building of an equitable society. But the argument, liberals contend, will not be over whether Islam should be part of the government, but instead over what type of secularism fits best.

Uskul argues that Turkey's bid for European Union membership, pushed by Erdogan's AK party, has set it on a course of democracy that virtually guarantees secularism. "The AK party is Turkey's reality," he said, chewing a cracker at a kebab restaurant. "Turks have to accept it. But it should proceed by showing it's not a threat to Turkey. I am an example of its willingness to reform."