( AP ) - Unite, unite, unite," the demonstrators shouted. This was an anti-government rally, but many of the slogans weren't meant for Turkey's ruling party.
They were directed at the country's opposition parties - a jumble of leftists, nationalists and others with often competing interests but at least one thing in common - the fear that Prime Minister Recep Tayyip Erdogan has an Islamic agenda.
But is that enough to offset their differences and guarantee them victory in elections this July? The answer is likely to depend on whether the opposition can offer a compelling vision of its own for Turkey's future.
Erdogan is credited with rescuing the economy and undertaking democratic reforms as part of Turkey's bid to join the European Union. He also has a powerful organization at the grassroots level, and supporters keen to express themselves at the polls.
But his government faces a secularist backlash over suspicions that he seeks to roll back restrictions on Islamic dress, curb women's rights and take other steps to dilute the Western lifestyle of many Turks.
His political rivals hope to exploit that fear at the polls, and for the first time since it took power in 2002, the Justice and Development Party is on the defensive.
"A second electoral triumph for Erdogan is far from assured," Bulent Aliriza of the Washington-based Center for Strategic and International Studies wrote in an analysis.
The election was set for July 22, several months ahead of schedule, as a way to ease a political crisis that began when the government picked a presidential candidate with strong Islamic leanings - Foreign Minister Abdullah Gul.
Although he and Erdogan say they don't want to blur the line between religion and state, Gul was forced to drop his bid after the opposition boycotted parliamentary votes on his candidacy, and the military threatened to intervene to safeguard secular traditions. Huge crowds staged anti-government rallies, most recently on Sunday in the port of Izmir.
The opposition could benefit if it successfully steers debate away from the government's economic record, which includes a growth rate of about 7 percent in the last several years and a sharp rise in per capita income, and casts the contest as a struggle for Turkey's identity, or Islam vs. secularism. That strategy already appears to be in motion.
"We have to stand hand in hand and protect Turkey," said Deniz Baykal, the 68-year-old leader of the Republican People's Party, which holds 152 seats in the 550-seat Parliament.
The ruling party, which only won one-third of the popular vote, has 352 seats, or nearly two-thirds, because most other parties failed to pass a 10 percent vote threshold required to win representation in Parliament.
Currently, Baykal's party is negotiating alliance terms with the Democratic Left Party, a group that failed to get into Parliament in 2002. The rivals draw support from the secular elite, including teachers, judges, doctors and military officers. Rebuilt after a military coup in 1980, their platforms revolve around their leaders' personalities as well as ideology.
Baykal and Zeki Sezer, leader of the Democratic Left Party, attended the huge demonstration in Izmir, but they did not stand together and shake hands as many protesters had hoped.
Analysts say the smaller Democratic Left Party wants enough seats in any alliance with the Republican People's Party to break away and form its own group once in Parliament. The Republican party is eager to avoid such an outcome because it doesn't want another competitor in the legislature.
There are even divisions within the Republican People's Party, the largest challenger to Erdogan's government. Baykal is viewed by some party members as out of tune with a changing Turkey. His supporters have criticized many aspects of Turkey's bid to join the EU, and a big part of their platform consists of recycled tributes to secularism enshrined in the Constitution.
Separately, two conservative parties merged as the New Democrat Party, which could help them pass the 10 percent voting margin. The conservatives plan to woo Turks who had supported Erdogan in 2002 to show displeasure with the previous government, but now want a less polarizing alternative.
Another player is the Nationalist Action Party, a far-right group that has capitalized on resentment toward the European Union for what some Turks view as arrogance and interference. It received just over 8 percent in the last election and did not make it into Parliament, but might succeed this time if it can harness a piece of the national mood.
Erdogan's party will seek to retain its large majority, an outcome that could avoid a weak coalition government with little appetite for bold policy. But it would shut the secularists out of power, possibly polarizing the country even further.
"The military has made clear that it might intervene if needed," said Nihat Ali Ozcan of the Economic Policy Research Institute in Ankara.