The decision in this regard was taken after four AICC observers led by Defence Minister AK Antony took the views of newly-elected MLAs on the issue of chief ministership.
Siddaramaiah, who is a backward caste leader from the Kuruba community, met former External Affairs Minister S.M. Krishna for about 20 minutes earlier in the day to seek his support for the coveted post.
Siddaramaiah, who was virtually the face of the Congress Party in the Karnataka assembly election, will be the 22nd chief minister of the state.
Siddaramaiah had earlier on Wednesday said he is confident that the national leadership would back him to become the state's new chief minister.
"Let us see, I am confident that national party will certainly back me. The question of management doesn''t arise at all. See, it is left to the legislature party and the high command. Let us see what decision the high command takes ," he told the media in Bangalore.
Congress made a spectacular come back in Karnataka wresting power after seven years in its old southern fortress. The party won 121 seats in the 224-member assembly.
The BJP and Janata Dal (Secular) finished second with both winning 40 seats each.
Yeddyurappa's KJP won six seats, while the independents and others won 16 seats.
Elections in Karnataka were conducted for 223 seats. Elections in one constituency - Periyapatna -- was deferred to May 28 due to the death of the BJP candidate.