Transport Minister Binali Yildirim is set to be appointed head of Turkey's ruling party and the new prime minister Sunday, consolidating the grip on power of strongman President Recep Tayyip Erdogan.

The 60-year-old replaces in both jobs Ahmet Davutoglu, a former foreign minister who promoted his own ambitious agenda but threw in the towel after a power struggle with Erdogan.

Yildirim -- a longstanding and faithful ally of Erdogan -- is the only candidate at an extraordinary congress of the ruling Justice and Development Party (AKP) that will choose the party chairman.

In a carefully-choreographed sequence of events, Erdogan is due later Sunday to hand Yildirim the mandate of prime minister, with a new government expected to be formed in the next days.

Analysts expect Yildirim to be a more pliant figure for Erdogan than Davutoglu, as the Turkish strongman presses on with his plan to create a presidential system in Turkey to further consolidate his powers.

Erdogan first came to power as prime minister in 2003, switching to the presidency in 2014. If he seeks a second presidential mandate in 2019, he could stay in power until 2024.

- 'More harmony' -

Transport minister for almost all of the last one-and-a-half decades, Yildirim has been Erdogan's pointman for the implementation of his grandiose road and rail infrastructure projects.

‘There appears to be more harmony’ between Yildirim and the president than in the Davutoglu era, Deniz Zeyrek, the Ankara bureau chief of the Hurriyet daily, told AFP at the congress.

‘Binali Yildirim is a more technocrat figure and a man of projects,’ he said.

He will be just the third party chairman in the history of the AKP -- which has transformed Turkey by putting Islam at the forefront of the officially secular country's politics -- after Erdogan and Davutoglu.

Not known for charisma, Yildirim made a glitzy entrance in front of thousands at the congress, clad in football scarves and throwing carnations into the crowds to the sound of thumping Turkish pop music.

Erdogan was not at the congress, with existing rules stipulating the head of state should not be a member of a party, something Erdogan may want to change in a new constitution.

But Justice Minister Bekir Bozdag made no secret of who he thought was the guiding light of the AKP.

‘It's impossible to think of the AKP as separate from our President Recep Tayyip Erdogan,’ he said. ‘The AK Party is Tayyip's party.’

In a message from Erdogan read by Bozdag, the president said: ‘The day I was sworn in as president, my legal bonds might have been cut (with the party) but the bonds of my heart with you have never and will never be cut.’

Despite rumours he is privately deeply embittered over his exit, Davutoglu also addressed the congress as the AKP sought to put on a show of unity.

‘It is not a congress of farewell but loyalty,’ Davutoglu said. ‘The AK Party's unity is more important than anything for me.’

Divisions between Davutoglu and Erdogan had been boiling for months over a series of issues including Turkey's battle against Kurdish militants, an accord with the European Union on refugees and the shift from parliamentary to presidential system.

Erdogan's critics have accused him of authoritarianism, pointing to prosecutions of journalists along with a highly controversial bill adopted by parliament on Friday that would lift immunity for dozens of pro-Kurdish and other MPs and could see them evicted from parliament.

Heading on a visit to Turkey, German Chancellor Angela Merkel voiced ‘great concern’ over recent political developments in the country.

- 'Calamity of terror' -

Another critical task facing the new prime minister will be to negotiate with the European Union on a crunch visa deal, a key plank of an accord aimed at easing the EU's migrant crisis.

The visa deal has been in jeopardy over Ankara's reluctance to alter its counter-terror laws, a requirement of the agreement, prompting Erdogan to make a series of critical statements about the EU in recent weeks.

Both Erdogan and Yildirim are strongly opposed to resuming talks with the outlawed Kurdistan Workers' Party (PKK), the Kurdish militant group that has killed hundreds of members of the security forces since a two-year-long ceasefire collapsed in 2015.

Yildirim vowed last week to ‘rid Turkey of the calamity of terrorism’ during a symbolic visit to the mainly Kurdish city of Diyarbakir in the southeast.