To garner support for his own candidature as President, former Lok Sabha speaker PA Sangma knocked the doors of UPA's maverick ally - Trinamool Congress chief Mamata Banerjee. Sources close to Banerjee said Sangma had personally called up the West Bengal chief minister and sought an early appointment to meet her in Kolkata. Sangma also reportedly sought an appointment with Congress president Sonia Gandhi and is awaiting a response.