The announcement was made by All India Congress Committee General Secretary Janardan Dwivedi, who said party chief Sonia Gandhi has approved the move.
Son of late Chief Minister R Gundu Rao, Dinesh is a three-time MLA and has been a national spokesperson of the party.
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At present, Home Minister G Parmeshwar is also the Pradesh Congress Committee (PCC) Chief.
There has been talk of Energy Minister D K Shiva Kumar likely to be made the PCC chief.
Chief Minister Siddaramaiah on Sunday dropped 14 ministers and inducted 13 members into his Council of Ministers in a bid to give a face-lift to his three-year old government.
Assembly elections in the state are two years away.