Sunak emerged as a winner by default in the contest to replace Liz Truss after two other contenders, House of Commons leader Penny Mordaunt and former Prime Minister Boris Johnson, had dropped out.
He now finds himself in an unenviable position of having to guide the UK out of the economic crisis while also having to mend the rifts inside the party created by his predecessors, both of whom resigned amid public scandals, marring the Tories' reputation and plunging their public support to historic lows.
"Many Conservative MPs will feel relieved at the chance to unite behind Rishi Sunak, who is not divisive by nature. Unfortunately, there are others who will never forgive Sunak because of his principled decision to resign from Boris Johnson's cabinet, as well as ordinary party members who are angry because they preferred Liz Truss to Sunak when they were given the chance to vote," Mark Garnett, a senior lecturer at the department of politics, philosophy and religion at Lancaster University, explained.
Sunak will start facing major challenges once he tries to appoint a cabinet that represents various factions within the party and has to fire prominent ministers, which will increase the number of his enemies in a parliamentary party that seems unwilling to submit to any kind of discipline, the expert said.
"Once that first challenge is over, Sunak will have to be ready for renewed arguments over the key statement on economic policy which is expected at the end of this month. Any sign of disunity among Conservative MPs will add to the existing demand for the general election which the party is desperate to avoid for two more years," Garnett added.
Meanwhile, Robinder Sachdev, the president of the Delhi-based think tank ImagIndia, suggested that Sunak has been anointed as Doctor Hope of the UK, describing the new prime minister's situation with the English proverb "when life gives you a lemon, make lemonade."
"Sunak needs to make some lemonade now. Doctor Hope, or 'The Lemonade-ist', whatever you call him, his immediate task is to prevent the UK from becoming the sick man of Europe at the start of 21st century," Sachdev said.
Sachdev pointed out that Sunak is the first non-white UK prime minister as well as the first practicing Hindu and the youngest one in 200 years to boot.
"His rise will have a huge inspirational impact on Indian Diasporas globally – especially the youth, children, and future generations of Indian-origin, worldwide. This will also raise the overall global image of the Indian Diasporas as competent technocrats, engineers, global CEOs, academics, scientists, Wall Street bankers, and more," the expert said.
At the same time, Sunak's Indian roots may prove to be a double-edged sword since he will always have to be careful to avoid being seen as granting special dispensations to his ancestral homeland and able to present all cooperation with India as beneficial to his UK constituents, according to Sachdev.
"Thus, while Sunak may personally much appreciate the potential upside to the UK of having wider and stronger UK-India relations, he will be extra-cautious in UK-India relations," Sachdev said, adding that while some might see this as a downside for India, this could also bring great benefits to both countries.
The expert also noted that there are multiple areas in which the two countries can work out a "ground-zero of collaboration which will be built on solid facts" and suggested watching out for the free-trade negotiations between London and New Delhi.
"You will see the rise of a technocrat led, number-crunching relationship between the UK and India in the future. The FTA negotiations between the UK and India will set the foundations, colors of UK-India relations in this decade," Sachdev concluded.