Erdogan rejoined the ruling Justice and Development Party (AKP) on May 2 after the public approved changes to create an executive presidency on April 16.

Under the old constitution, the head of state had to sever ties with their political party and Erdogan left as AKP chairman in August 2014 after his election as president.

Rejoining the AKP was the first major change permitted after the vote, allowing the president to be affiliated with a political party almost immediately.

Erdogan narrowly won with 51.4 percent of the vote but most of the new system, including axing the role of premier, will not come into force until November 3, 2019.

However, as leader Erdogan can decide the party’s direction.

Current party leader and Prime Minister Binali Yildirim will be given a newly-created role of “vice chairman”, AKP deputy chairman Hayati Yazici said on Saturday.

Erdogan led the party for three terms during his premiership between 2003 and 2014, after he co-founded it in 2001.

The father-of-four affectionately describes the most effective Islamic rooted political force in the history of modern Turkey as his fifth child.

After becoming a party member again in an emotional grand ceremony in Ankara, Erdogan said he had “returned to my home, my passion, my love”.

With Erdogan as party leader, all eyes will be on the cabinet, with Hurriyet daily speculating at the weekend that eight to 10 ministers could be reshuffled.

Era of transformation

Nearly 1,500 delegates will vote to decide the new party leader, state-run news agency Anadolu reported, in an election where there is only one candidate: Erdogan.

If chosen, it will be the first time the president will be both party chairman and head of state since the end of the presidency in 1950 of Ismet Inonu, the successor and right-hand-man of Mustafa Kemal Ataturk, Turkey’s modern founder.

In the capital and on social media posters and images have appeared of Erdogan and slogans such as “iron will, strong Turkey” and “full steam ahead with the founding leader”.

A special congress slogan reads “a new breakthrough period: democracy, transformation, reform” hinting at the expected restructuring of the government as well as changes to the party’s executive in the coming weeks and months.

Erdogan told party officials “the new period means a new action plan” without giving details, Hurriyet reported on Saturday.

Up to 60,000 participants from across Turkey are expected to descend on Ankara for the congress in the stadium in the city centre, Anadolu reported.

‘Party full of loyalists’

Turkish pro-government media has been full of AKP officials speculating that Erdogan’s return will mean the end of the party’s internal rivalries and will boost morale.

According to Aykan Erdemir, senior fellow at the Foundation for Defense of Democracies, Erdogan “could informally dictate the AKP’s MP candidates to a great extent” even after leaving in 2014.

But the former MP for Turkey’s main opposition Republican People’s Party (CHP) said becoming chairman would mean Erdogan gains the “formal authority to determine who runs for office from AKP lists”.

Erdemir told AFP: “This new prerogative will allow him to design both a party apparatus and a parliamentary group composed entirely of loyalists.”

Well-connected Hurriyet columnist Abdulkadir Selvi previously said Erdogan would oversee a oversee a shake-up of AKP leaders at local level determined by their success in the referendum.

“The most crucial outcome of his power grab within the AKP is that as the president-cum-party leader, Erdogan will hold the reins of the lawmakers who are supposed to check and balance the executive, and impeach the president, if necessary,” Erdemir said.

“Hence, by becoming the AKP leader, Erdogan wants to make sure that he has enough loyalists in the parliament to block any impeachment attempts.”