64-year-old Siddaramaiah, who was sworn in as the Chief Minister on May 13 marking return of Congress to power after a seven-year hiatus, however, said there would be no Deputy Chief Minister.
The Chief Minister said the focus of the cabinet expansion would be on "region and social justice".
A section within the Congress has strongly pushed the party leadership not to give Cabinet berths to those allegedly involved in illegal mining scam and facing corruption charges.
Meanwhile, the Speaker's post may go to octogenarian MLA Kagodu Thimmappa, who won from Sagara in Shimoga District.
"We are thinking of Kagodu Thimmappa," Siddaramaiah said.
But Thimmappa has reportedly turned down the proposal.
Siddaramaiah said there would be no Deputy Chief Minister, a post eyed by Karnataka Pradesh Congress President G Parameshwara, who lost the May 5 Assembly poll from Koratagere in Tumkur district, and senior MLA T B Jayachandra.
Swearing-in ceremony of the new Ministers -- expected to be 20-plus -- will be held at the Glass House in Raj Bhavan, with Governor H R Bhardwaj administering the oath of office.
The names doing the rounds for Cabinet berths include Jayachandra, R V Deshpande, H K Patil, Shamanur Shivashankarappa, Ramanatha Rai, Ambarish and Ramalinga Reddy, according to Congress sources.
