Singh had on Saturday written to Gandhi, apprising her of his decision.
He said the political events of the last about five months were "clearly not based on full understanding of the national imperatives of Punjab and its key concerns."
"Notwithstanding my personal anguish, I hope this will not cause any damage to the hard-earned peace and development in the state, and that the efforts I have been focusing on during the last few years would continue unabated, ensuring justice to one and all," Singh wrote in his letter to Gandhi, indicating his apprehension of instability in Punjab as a result of the political developments in the state unit of the Congress.
At the same time, he expressed satisfaction at having done his best for the people as the chief minister of Punjab, which, as a border state, "has many geo-political and other internal security concerns, which I tried to handle effectively without any compromise."
He said he was happy that the state remained "fully peaceful, and there was complete communal harmony with no ill-will towards anyone".
While she (Sonia) herself may be personally aware of some of the things achieved in the last four and a half years, "the people of Punjab are looking up to the Indian National Congress for its mature and effective public policies, which not only reflect upon good politics, but also address the concerns of the common man that are specific to this border state," wrote Singh, while informing the Congress president about his decision to demit his post.
On the issues on which his government has faced criticism from not just the Opposition but also from a section of party''s state leaders, he gave details of various steps taken by his government on the sacrilege incident and other such issues including the drug menace.
Congress veteran Singh resigned as chief minister of Punjab months ahead of the Assembly polls after a bruising power struggle with state party chief Navjot Singh Sidhu.
After submitting his resignation to the Governor on Saturday, Singh said he felt "humiliated" over the way the party handled the protracted crisis. The 79-year-old Singh, one of the Congress'' powerful regional satraps, had put in his papers after speaking to the party president and shortly before a crucial meeting of the CLP here on Saturday evening.
Notwithstanding "numerous challenges" faced by him over the last four and half years in delivering on the promises made by the state Congress in the 2017 Punjab Assembly elections, "my government fulfilled 89.2 per cent of the promises, while work is in progress on the remaining commitments", Singh said.
On the issue of the sacrilege cases and the subsequent police action of 2015, for which his government came under criticism not only from the Opposition but some leaders from the party''s state unit questioning him for not doing enough, he said the government which he earlier headed was committed to ensuring justice in the matter.
The government had established a Judicial Commission of Enquiry headed by retired judge Ranjit Singh, whose report was received on August 16 2018. The report was accepted and full legal action was taken thereon, he said, sharing details of the same.
He pointed out that despite legal hurdles and refusal of CBI to return the cases, which were transferred to them by the SAD-BJP government, his government had succeeded in filing 10 challans, while 24 people had been charge-sheeted, 15 police personnel suspended, and 10 civilians arrested.
"Criminal proceedings in these cases are currently underway and I am sure that justice will be done in due course," he said.
With regard to the power purchase agreements that were signed by the previous government, he said, "the review of the PPAs is currently under way."
He also touched upon the steps taken for farming community which included giving debt relief and repeal of statutory provisions of attaching their properties.
Referring to his promise to the people of Punjab at the time of previous assembly polls to break the back of drug peddlers and smugglers in the state, he said he had done so relentlessly by establishing a Special Task Force (STF).
He said 62,744 people were arrested and 202 OOAT (Opioid Assisted Treatment) clinics established, among various other steps taken.
Singh served as the chief minister from 2002-2007 and from March 2017-September 18, 2021.
In these nine and a half years, he wrote in the letter, that he had worked wholeheartedly for the welfare of the people of Punjab --the state he loves from the core of his heart, and ensured transparent governance.
According to a statement, the letter also mentioned about Congress winning eight out of 13 seats in the Lok Sabha elections in 2019 and the Panchayati Raj and Urban Local Bodies polls decisively.