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, is in line with the party's declared 'One person, One post' principle that was announced at the Udaipur 'Chintan Shivir' in May.