Turkey's president has called for a referendum on whether the next president should be elected by the people instead of by Parliament.
Ahmet Necdet Sezer called for the referendum after parliament voted for a second time to change the constitution to allow popular election of the president.
Mr. Sezer, who already vetoed the measure once, had to either approve it or call the referendum.
Turkey's ruling Islamist-rooted AK Party proposed the reform package after parliament failed to elect its candidate for president, Foreign Minister Abdullah Gul.
Secularists opposed Mr. Gul's candidacy for president, and they have accused the AK Party of attempting to undermine Turkey's secular order.
Prime Minister Recep Tayyip Erdogan has said he is committed to Turkey's secular system.
Mr. Erdogan also called for early parliamentary elections over the political deadlock.
Some information for this report was provided by AFP and AP.