Senior Congress leader Mallikarjun Kharge has resigned as the Leader of Opposition in Rajya Sabha, sources said on Saturday, a day after he filed his nomination papers for the AICC president's election.

Kharge's resignation, which the 80-year-old leader sent to Congress president Sonia Gandhi on Friday night, is in line with the party's declared 'One person, One post' principle that was announced at the Udaipur 'Chintan Shivir' in May.