The Turkish Prime Minister Recep Tayyip Erdogan has pledged to re-write the country’s constitution, as he launched his presidential campaign for the election in August.

Barred from seeking a new term as premier, he has made little secret of his desire to boost significantly the powers of the president, who will be directly elected by the people for the first time.

“We put up a strong fight to have a new constitution, to make a freedom supporting, democratic and outward-looking constitution. We failed, because of those whose mentality is that of the ‘old Turkey’. But we haven’t given up hope over it. And we will continue to fight for it as forcefully as possible,” Erdogan told several thousand supporters in an Istanbul conference hall.

The combative prime minister has endured one of the most challenging periods of his political career, facing down widespread anti-government protests and a corruption scandal over the past year, as well as contending with a deepening security threat posed by chaos in neighbouring Iraq and Syria.

In his speech, Erdogan also vowed to deepen democracy and give Turkey a more prominent role on the world stage.

But his main challenger, Ekmeleddin İhsanoğlu, has echoed fears that the man who has dominated Turkey for over a decade intends to become even more autocratic.

“The president is head of the family and shouldn’t be a man with a stick beating everyone over the head,” İhsanoğlu, 70, said late on Thursday as he unveiled his strategy at a markedly more reserved event.

Opinion polls however suggest a comfortable win for Erdogan; two surveys late last month gave him a 20-point lead over his rival.

If no candidate wins more than 50 percent in the first round on August 10, a runoff vote will be held on August 24.