Thousands of Turks held anti-government demonstrations Saturday. The rallies in defense of Turkey's secular system come ahead of a key vote in the Turkish parliament to elect a new president. As Amberin Zaman reports from Istanbul, the presidential election has evolved into a showdown between Turkey's pro-Islamic government and pro-secular forces in the opposition and in the military.

Demonstrators march during a pro-secular rally in Manisa, western Turkey, 05 May 2007

Waving Turkey's crimson national flag and chanting anti-government slogans, more than ten thousand demonstrators marched through the western city of Manisa on Saturday. Their message was the same as in a mass rally held last week in Istanbul: "Turkey is secular and must remain so." Further west in the city of Canakkale thousands more staged a similar protest.

Meryem Tuna is a middle-class homemaker from Istanbul who has taken part in anti-government demonstrations. Like others opposed to the government, she is worried that Turkey's pro-Islamic prime minister, Recep Tayyip Erdogan, has nominated his foreign minister, Abdullah Gul, to replace the incumbent Ahmet Necdet Sezer as president when he steps down on May 16.

Tuna says the main problem with Gul is that his wife wears an Islamic style headscarf and will therefore project a backward image of Turkey, one that directly contradicts the kind of Turkey Ataturk envisioned when he encouraged Turkish women to abandon their veils and gave them the right to vote even before their peers in France and Switzerland.

For Turkey's main opposition parties, it is about more than just Turkey's image. They say if both the government and the presidency are controlled by Islamists, Turkey's secular system will be overturned. At the end of April, they boycotted a first round of voting in the parliament to elect a new president.

Gul, who is running unchallenged for president, suffered a further setback when the constitutional court upheld the opposition's claims that there were not enough deputies present at the session and it was therefore invalid.

The court delivered its verdict only days after the military issued a statement on its Web site listing the risks posed by Islamic fundamentalism and threatened to intervene if need be. The move was sharply criticized by the European Union.

The E.U. is demanding that the military's powers be trimmed before Turkey is admitted as a full member of the 27 member bloc.

Onur Oymen is deputy chairman of the staunchly pro-secular main opposition Republican People's Party, which was founded by Ataturk. He disagrees that the military was in breach of democratic principles when it delivered its ultimatum last week. "They expressed in a strong way maybe their opinions but they stated in their statement that everybody needs to observe the rules of the constitution - that was their message. The constitution and the basic principles of the constitution starting with secularism," he sad.

Oymen adds that he does not believe that the Turkish army, which has overthrown four governments since 1960, will seize power ever again.

The government will attempt for a second time on Sunday to elect Gul. Should it fail to do so, Erdogan has said he will hold nationwide general elections on July 22, well ahead of the originally scheduled date, November 4. He is also pushing for constitutional changes that would allow the Turkish people to elect a president themselves

Two center-right opposition parties - the True Path and Motherland - announced Saturday they are uniting as the Democrat Party in order to challenge the ruling party in July 22 elections.