External Affairs Minister Salman Khurshid is understood to have decided to go by seniority and has recommended Ms Singh, a 1976 batch officer who would be the third woman to head the country's foreign office, after Chokila Iyer and Nirupama Rao. The appointments committee of the cabinet is said to have cleared her appointment. A formal announcement is expected soon.
Ms Singh's husband Sanjay Singh was also in the foreign service and retired recently as Secretary (East).
The top diplomat is the daughter of TV Rajeshwar, a former governor and Intelligence Bureau chief. Congress president Sonia Gandhi had recently attended the 60th wedding anniversary of Mr Rajeshwar, in what many said was an implicit nod to her appointment.
The other contenders for the coveted job were S Jaishankar, India's ambassador to China, Jaimini Bhagwati, Indian High Commissioner to Britain, Sudhir Vyas, Secretary (West) and Pinak Ranjan Chakravarty, Secretary (Economic Relations) in the Ministry of External Affairs.
Ms Singh's appointment will put an end to speculation that Mr Jaishankar, who is junior to her, as well as to Mr Vyas and Mr Chakravarty, will get the top job.
In going for Ms Singh, the government has indicated that it does not want to rock the boat of the foreign service where discontent had been building up on reports that Mr Jaishankar, who had helped defuse the boundary crisis with China, might be the chosen one. Mr Jaishankar is the son of late K Subrahmanyam, the eminent strategic policy analyst.
The government had to face discontent earlier when it chose Shivshankar Menon as foreign secretary in October 2006 over the heads of 15 IFS officers. It had triggered a minor revolt with then Secretary (East) Rajiv Sikri submitting his resignation and two envoys - TCA Rangachari, ambassador to France, and Veena Sikri, the wife of Rajiv Sikri and then High Commissioner to Bangladesh - putting in their papers as well. Mr Rangachari was next in seniority to then outgoing Foreign Secretary Shyam Saran.
After Mr Menon retired as foreign secretary in July 2009, the government chose the next two foreign secretaries, Nirupama Rao and then Ranjan Mathai, on the basis of seniority.
There were fears that if the government had gone in for Mr Jaishankar, it would have triggered a 2006-like situation, leading to senior diplomats - much-feted for their work - putting in their papers, a situation the government would like to avoid in a politically-surcharged year leading up to the general elections.
The tenure of a foreign secretary is two years.