When Turkey's ruling AK Party convenes its three-yearly congress in the capital Ankara on Saturday, the longest shadow will be cast by a politician who, officially at least, is no longer even a member: President Tayyip Erdogan.The most popular and divisive Turkish politician in recent memory faces budding discontent from inside the movement he founded, officials say, as his drive to secure an absolute majority for the AKP has pushed it toward a snap election where such a result is uncertain.The friction between Erdogan and the man who replaced him as head of the AKP, Prime Minister Ahmet Davutoglu, is likely to play out on Saturday as both men attempt to stack the party's committees with their own loyalists.There had been some speculation that Erdogan would push former transport minister Binali Yildirim to challenge Davutoglu as chairman of the centre-right, Islamist-rooted AKP at the congress.However, party spokesman Besir Atalay confirmed on Friday that Davutoglu would stand for the leadership unopposed."He seems to have scared Davutoglu into toeing his line by raising the specter of his man Binali Yildirim contesting the leadership," said Halil Karaveli, managing editor of The Turkey Analyst, a policy journal.Party officials say that, among numerous bones of contention within the ranks, there is much argument over the fact that Davutoglu considered forming a coalition after the AKP lost its absolute majority at an election in June. Erdogan's hope is that the AKP can win enough votes to eventually change the constitution and create a more powerful presidency, though this looks highly unlikely in the short term.After the AKP failed to find a junior coalition partner, Davutoglu was forced to form a temporary cabinet.INVESTORS WORRIEDThe political uncertainty has already worried investors in Turkey's more than $800 billion economy, who have been unnerved as Ankara battles Kurdish militants at home and Islamic State fighters on its borders, and have sent the lira currency to a series of record lows.As president, Erdogan is supposed to be above party politics, but party officials say he still exerts enormous influence over the AKP, and will make this felt as members of the party's powerful committees are chosen."Some of Erdogan's more drastic authoritarian moves are likely the result of political survival instincts," said Erik Meyersson, an assistant professor at the Stockholm School of Economics."In practice, this would mean retaining control over leadership of the party - somewhat peculiar given that he's not the official head of the party any more - and appointing lieutenants personally loyal to himself."One senior AKP official said this would annoy some factions, but that there was little they could do about it. "Nobody can risk a massive breakup, and everyone is aware of this sensitivity," the official said.Suleyman Ozeren of the Global Strategic Research Centre agreed that feathers would be ruffled, "but it must also be accepted that the one who controls the party is President Erdogan".