Thousands of people gathered near Ankara's main railway station on Sunday, close to the scene of the twin bomb attacks which killed an estimated 128 people.
Government opposition groups chanted "Murderer Erdogan", "murderer police", blaming the president for the worst terrorist attack in the country's history.
Turkey said it believes the so-called Islamic State group to be behind the attacks with state TV saying 43 people had been detained in dawn raids across the country.
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The Democratic presidential candidate may also have shown his cards on his choice of running mate.
The US president also shared a post on Twitter accusing Dr Anthony Fauci of misleading the public over hydroxychloroquine.
Fears over an impending second wave of coronavirus dominates Wednesday’s front pages.