"The observers will brief the party high command (on legislators' choice) which will take the decision," Siddaramaiah, who was leader of the opposition in the outgoing assembly, told reporters at his residence in Bangalore.
On the support he has among the legislators to become the chief minister, he said: "All 120 MLAs (members of the legislative assembly) are with me."
He did not give details of who would be coming as observers and when the decision on chief minister was likely to be announced.
The Congress won 121 seats in the 225-member assembly on Wednesday when votes polled Sunday were counted.
"I am a strong contender," Siddaramaiah had said on Wednesday even as vote count was on and trends showed that the Congress was heading for a clear majority in the house.
Another top state Congress leader who has shown keenness to lead the party's government in the state after seven years is Union labour and employment minister Mallikharjun Kharge.
He had said on Wednesday that if the high command thinks he was fit for the post, it was for it to take the decision. However, he had said he did not want to be considered because he is a Dalit.