If the court upholds the opposition appeal, the government would have to call a snap general election, a key demand of smaller opposition parties.




"If the presidential election is cancelled [by the Constitutional Court], chaos will ensue," said the Radikal daily newspaper.


CHP leader Deniz Baykal repeated his threat on Friday to prevent Gul's election.


"The presidential election has been handled very wrongly. We are in a very confused situation," he told CNN Turk television.


"The president must be loyal to the main principles of the Republic as stated in the constitution"

Abdullah Gul, presidential candidate


Opposition parties accuse the AK Party of failing to consult with them on its choice of candidate.


The ruling AK party is 15 seats short of the required majority.


Ruling party officials have therefore been holding meetings with independent ministers and the leaders of the centre-right Motherland and True Path parties, who together control 24 seats, to garner support.


If they fail, Gul may not be formally confirmed in his new post until after a third round of voting on 9 May, when only a simple majority in the 550-seat chamber would be required.




Gul has rejected the label of Islamist, citing his promotion of sweeping reforms as a means of advancing Turkey's EU bid.


"The president must be loyal to the main principles of the Republic as stated in the constitution. He must be loyal to secular principles," Gul said. "If the Parliament elects me president, no one should doubt I will certainly act within these principles and rules of the constitution."


AK party leaders remain confident of securing a first-round victory for Mr Gul.

"In my view, everything is very clear," Bulent Arinc, the speaker of parliament, told reporters.