President Recep Tayyip Erdogan and his main opponent staged massive rival rallies Sunday, setting the stage for a bruising battle in the final two weeks of Turkey's election campaign.

The veteran Turkish leader filled a central Ankara square that can fit a few hundred thousand people with flag-waving supporters, showing no signs of an illness that sidelined him for three days this week.

"Are we ready to come out with a crushing victory?" Erdogan, draped in a scarf of the Turkish capital's main football club, demanded from the enthusiastic crowd.

"On May 14, our nation, God willing, will eliminate them from the political scene," he said of secular leader Kemal Kilicdaroglu and his six-party opposition alliance.

The 69-year-old president has bounced back strongly from what was described as a digestive problem in the run-up to one of Turkey's most important elections of its post-Ottoman history.

The illness shook Erdogan's strongman image, which he has cultivated over two decades of economic booms and busts, social transformation and crackdowns on dissent.

"As you know I was sick recently, and from every house, people were praying for me," Erdogan told the crowd.

"I am trying to be worthy of those prayers."

Kilicdaroglu, 74, and his multi-faceted alliance are posing Erdogan's toughest election challenge since the Turkish leader's Islamic-rooted party first swept to power in 2002.

Erdogan became prime minister a year later, consolidating control as a powerful president under a new constitution in 2018.