"The Tale of Two, An Outgoing and An Incoming, Prime Minister", a self-published work (AuthorsUpFront), brings together images of contrast of Singh and Modi in public and their positions in their parties.
According to Rai, since a prime minister is the supreme leader of a nation, there is "no room for us to look for the detractors who might have been the cause of his failure".
He says in Singh's case, his "failure to give us the kind of government we wanted might have been because of the high command's final decision or the scams caused, but the sole responsibility falls upon the prime minister of the day".
Rai says similarly when Narendra Modi takes over, "his performance as prime minister will have to be judged by his actions and decisions in performing his 'rajdharma."
The veteran photograph themed his book on two sessions of Congress and BJP held in the capital in January.
"It was after 25 long years, I found the courage to photograph once again the sessions of two leading political parties during election season, the Congress and the BJP," he says of the initiative.
"Though it was the month of January, the weather outside was pleasant but during those four hours I spent inside, there was a strange kind of stuffiness in the arenas A strange kind of sycophancy and personality cult is entrenched in both the parties; as if the other members are lesser beings who seem entirely accepting of their lowly status," he writes.
On January 17, Rai spent four hours at the All India Congress Committee (AICC) session held at Talkatora stadium in the capital and photographed the mood with a special focus on the then Prime Minister Singh.
The photographs used in the book were taken between 9.30 AM and 1.30 PM on that day. Next day when Rai went through the pictures on his computer, he says he was "pained by what I saw".
"Earlier on I have photographed and experienced in various political sessions of leading parties, relationships, manipulations, sycophancy and power play. But the prime minister of the day used to be the focus of attention and interest and everyone in the party looked up to him for an interaction or even a smile," he writes.
"In Mr Singh's case, he walks in behind Sonia Gandhi at 10.30 AM, and sits a few feet away looking lonely and isolated. There is only a tinge of a reluctant smile on his face when he stands between Sonia and Rahul Gandhi sharing a big garland meant for the trio," Rai writes.
He says that every moment he photographed Singh, there was the "same fixed expression of gloom on his face, as if he was living a nightmare".
According to Rai, the other sad part was, "in those few hours that I was there at the Congress session, nobody came to discuss or share anything with him as if he did not matter anymore. He looked isolated, ignored and deserted".
Rai was then at the BJP's National Council meeting at Ramlila Grounds on January 19 again from 9.30 AM to 1.30 PM.
"All senior leaders of BJP were presiding under larger-than-life headshots of Narendra Modi which formed the backdrop of the main stage Each of these leaders got up to speak, Modi's image looking out over their heads. It was clear that Modi was to be the projection of the day.
"Then Modi stood up to speak. A newly programmed, well-designed, well-worded campaign declamation came pouring out of him with proper emotional punctuations. The audience listened spellbound. He projected himself as a comprehensive and well-aware leader of a party that was missing ever since Vajpayee withdrew from active political life," Rai recalls.
"Now that he takes over as the new prime minister, apart from his hardcore critics, many in India have great hopes of him taking the country towards good governance," he says.