Greek Prime Minister Alexis Tsipras called for the European Parliament to join the so-called quartet of creditor institutions overseeing the country's 86-billion-euro EU/IMF bailout programme. "I deem it politically imperative that the sole European institution with direct popular mandate acts as the ultimate guarantor of democratic accountability and compatibility of economic policy in Europe," Tsipras wrote in a letter to European Parliament President Martin Schulz. Tsipras' office said Schulz reacted positively to his letter in a telephone conversation between the two.