Just how important he was for the BJP can be gauged from the positions the former army officer held during in recent years: minister for defence and finance, leader of the opposition in the Rajya Sabha, chairman of Public Accounts Committee which oversees government spending, and deputy chairman of the Planning Commission.
In 2012 he was the National Democratic Alliance (NDA) nominee for the vice presidential election but lost to incumbent Hamid Ansari.
Looking back, three defining moments stand out: a high and two low.
In 1999, Jaswant Singh was roundly criticised for accompanying three terrorists India released in exchange for passengers and crew of an Indian Airlines plane hijacked to Afghanistan while flying from Kathmandu.
A decade later, the BJP expelled him for his book "Jinnah: India, Partition, Independence" that praised Pakistan's founder Mohammad Ali Jinnah and blamed Jawaharlal Nehru for the country's partition.
The high of course was his deft negotiations with the US State Department that culminated in the balance restored in India-US ties with the visit of Bill Clinton in 2000.
Strobe Talbot, the US deputy secretary of state who held 14 meetings in seven countries, said in his book "Engaging India: Diplomacy, Democracy and the Bomb": "I hope my regard for the way Jaswant advanced his nation's interests and sought, as he put it, to harmonise US-India relations speaks for itself in these pages. Indeed, it is a major reason why I wanted to write about what we did, and tried to do, together."
Jaswant Singh, once a powerful minister in NDA govt, stands a loner today
Today, Jaswant Singh is for all practical purposes a long ranger who has been reduced to tears - literally - after being denied the party ticket to contest in his own home turf.