Watch: Rishi Sunak says he is proud of parents-in-law, Infosys founder Narayana Murthy and Sudha Murthy

In a televised discussion on July 18, former UK finance minister and potential candidate for prime minister Rishi Sunak addressed the controversies surrounding his family's wealth. His wife Akshata Murthy is the daughter of Infosys founder Narayana Murthy and author and educator Sudha Murthy. The tax arrangements of the former UK chancellor's family have long been a source of scrutiny. In the debate that ITV aired on Sunday, Sunak expressed his pride in the journey his parents-in-law had taken.

"My father-in-law came from absolutely nothing and just had a dream and a couple of hundred pounds that my mother-in-law’s savings provided him," Sunak said. "And from that, he went to build one of the world’s largest, most-respected companies, that, by the way, employs thousands of people here in the United Kingdom."

He added: "It is a story I am really proud of, and as prime minister, I want to ensure that we can create more stories like that at home."

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The 42-year-old former Chancellor, who was born in the UK, was grilled during a contentious television debate about his wife's tax affairs, which made headlines earlier this year when she voluntarily gave up her legal non-domicile status in order to pay taxes on her Indian income from shares of Infosys, which were also owned by the UK.

Regarding his own US Green Card, which he purportedly renounced after a few months in the Chancellor's position at No. 11 Downing Street, Sunak was also questioned.

The argument was the most recent face-off between the five surviving contenders for the position of new British Prime Minister and leader of the Conservative Party, succeeding Boris Johnson.

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Before the third round of voting by Tory MPs on Monday to further limit the field and get to the final two candidates, an instant opinion poll by Opinium indicated that Sunak was the undisputed winner of the discussion on Sunday.

At least one of the candidates with the fewest votes would be eliminated, and another round is anticipated on Tuesday. The former chancellor had the highest rating from the 1,001 participants in the Opinium survey—about 24%—followed by Tom Tugendhat, chair of the Commons Foreign Affairs Committee, with 19%. Penny Mordaunt, the minister of trade, came in third with 17%, followed by Liz Truss, the secretary of state, with 15%. The viewer poll placed former equalities minister Kemi Badenoch in last place with 12% of the votes.

However, a Conservative Home website poll of the party's grassroots members that was released on Sunday night indicates that Badenoch may be gaining in favour as she has emerged as their top choice, followed by Mordaunt.According to that poll, if Badenoch and Mordaunt made it to the final two, Badenoch would win in a head-to-head matchup 59 to 31 percent of the time. Mordaunt would likewise come up short against Sunak and Truss.

(With inputs from agencies)