The 48-year-old Mann was elected the AAP Legislature Party leader at a meeting of the party MLAs in Mohali on Friday.
Arvind Kejriwal elected AAP legislature party leader.
After securing a landslide victory and being elected leader of the Aam Aadmi Party legislature party, Arvind Kejriwal met Lt Governor Najeeb Jung on Tuesday evening and staked claim to form the government in Delhi.