78-year-old Singh, who has been invited by Governor Urmilla Singh to form the government, would take oath alone and will finalise his council of ministers later this week after consultation with Congress President Sonia Gandhi, sources said.
Singh met Gandhi in Delhi today to discuss the formation of the new government, they said. He was formally elected as the leader of the Congress Legislature Party in Shimla on Saturday.
Congress has 36 MLAs in the 68-member Assembly and one independent MLA has extended unconditional support to the party. Singh was Chief Minister between 1983 and 1985; 1985 and 1990; 1993 and 1998 and 2003 and 2007.
In his five-decade-long political innings, he has been a seven-time MLA, a five-time MP and a five-time Chief Minister.
He has also been a four-time President of the Himachal chapter of Congress and also represents the Mandi seat in the present Lok Sabha.
Singh had a long meeting with AICC General Secretary Janardan Dwivedi, who was deputed as observer by the party high command for Congress Legislature Party (CLP) meet, on Saturday evening in Shimla and discussed several key issues relating to government formation.
Singh, after the election as CLP leader, had told reporters that his ministry would be a three-tier one and "fully representative".
"All sections and regions, young and old would be included in the ministry," he had said..
Asked about the next speaker of the state assembly, Singh had said he had three persons in mind but would not divulge the names at this stage.