Turkish Prime Minister Ahmet Davutoglu has announced he will not stand again as leader of the ruling AK Party, bowing to President Tayyip Erdogan's drive to create a powerful executive presidency.
In a speech defending his record as prime minister but also vowing loyalty to Mr Erdogan, Mr Davutoglu said he had kept his party and the government intact during a tumultuous period in Turkey and pledged the "strong" AKP government would continue.
After a meeting of the party's executive committee, Mr Davutoglu told a news conference that under the current circumstances he would not run for the leadership of the AKP at an extraordinary party congress on 22 May.
"I am telling our members, up until today I was leading you. From now on, I am among you," he said, vowing to continue his political struggle as an AKP lawmaker.
Mr Davutoglu's departure plunges Turkey into political uncertainty just as Europe depends on it for help in curbing a migration crisis and as Washington draws on the NATO member's support in fighting the so-called Islamic State in Syria and Iraq.
Turkey could now face an early general election this year as Mr Erdogan pushes ahead with plans to strengthen the presidency.
Mr Davutoglu had offered only lukewarm support for Mr Erdogan's vision and his departure follows weeks of tensions.
His successor is likely to be more willing to back Mr Erdogan's aim of changing the constitution to create a presidential system, a move that opponents say will bring growing authoritarianism.
Mr Erdogan wants Turkey to be ruled by the head of state, a system he sees as a guarantee against the fractious coalition politics that hampered the government in the 1990s. His opponents say this is merely a vehicle for his own ambition.
"Palace Coup!" said the headline in the secularist opposition Cumhuriyet newspaper.
There could now be a third parliamentary election in less than 18 months.