Mr Erdogan's AK Party has sent plans to parliament allowing government more say over appointment of prosecutors and judges.
He argues a judiciary and police in the sway of the Hizmet (Service) movement of cleric Fethullah Gulen contrived a fraud investigation now shaking his administration.
The deputy head of the national police, Muammer Bucak, and provincial chiefs, among them the commanders in Ankara and Izmir, have been removed from their posts overnight.
The government has purged hundreds of police since the scandal erupted last month with the detention of dozens of people including businessmen close to the government and three cabinet ministers' sons. Among the dozens questioned, most have been released but 24, including two ministers' sons, remain in custody.