Erdoğan said the vote, originally scheduled for November 2019, was moved up to accelerate Turkey's change from a primarily parliament system to one giving the president more executive authority.
Yet Ince's greatest political assets are his rhetorical skills and impassioned speeches which have made him a favourite with the CHP faithful in recent years.
"He will be able to ensure a large turnout of the CHP electorate on election day".
Ince had previously tried to unseat Kilicdaroglu as the head of the party, but failed to gain enough support among party delegates to replace the chief, who has been in the job for eight years.
The elections will mark Turkey's transition to a presidency with new sweeping executive powers, agreed under a narrowly approved referendum past year.
He had famously vowed to sell off Erdogan's enormous presidential palace opened in 2014 should he be elected.
Gul said on Friday such a visit had taken place but denied there had been "any threat, imposition, or lack of respect".
Prime Minister Binali Yildirim said lawmakers of the Justice and Development Party, or AKP, agreed to back Erdogan during a meeting on Thursday.
He is a veteran of Turkish politics who has been a member of parliament since 2002 and has twice stood for leadership of his party. This has lead to speculation the CHP could pull its candidate in the second round of voting and back Aksener.