Congress today said the alliance between JD(U) and BJP in Bihar is rank opportunism and a treachery of people' mandate. <br/><br/>In a statement, Congress spokesperson Randeep Surjewala termed today as a black day for democracy. He said the hunger for power of Nitish Kumar, who was sworn in as Bihar Chief Minister today, has over powered everything else. <br/><br/>Mr Surjewala said the people of Bihar had rejected the leadership of Prime Minister Narendra Modi and the policies of BJP in 2015 during the assembly elections. He said mandate of people of Bihar was in favour of policies, principles and leadership of the Grand Alliance.