(Bloomberg) -- UK Prime Minister Rishi Sunak stood by Nadhim Zahawi, allowing the Conservative Party Chairman to stay in post while an investigation is carried out into his tax affairs.

Sunak’s remarks suggest he’s backing Zahawi for now, despite support ebbing away after the chairman of the ruling party said he’d been “careless” over tax payments relating to the the sale of shares in YouGov, the polling company he co-founded. 

“The politically expedient thing to do would be for me to have said this matter must have been resolved by Wednesday at noon,” Sunak said, referring to the start of his weekly question-and-answer session in the House of Commons. “But I believe in proper due process.”

Nevertheless, there’s been a change in tone since last week, when Sunak batted away a question about the matter. Then he said that Zahawi had “already addressed the matter in full and there is nothing more that I can add.”

The calculus changed over the weekend when Zahawi issued his statement, in which he also acknowledged settling a bill with the tax authority. The Guardian has said that bill totaled £4.8 million ($5.9 million), including a 30% penalty for not settling the correct amount at the right time. The settlement took place while Zahawi was Chancellor of the Exchequer in mid-2022.

“Since I commented on this matter last week, more information, including a statement by the minister without portfolio [Zahawi] has entered the public domain,” Sunak said in the Commons on Wednesday. “It is right that we fully investigate this matter and establish all the facts.”

Sunak on Monday commissioned an inquiry into Zahawi’s tax affairs, but has so far kept him in post amid mounting pressure from within the Conservative party for him to step aside or be sacked. 

There are also questions now surrounding the role played by Cabinet Secretary Simon Case, the head of the civil service, whose remit includes advising the prime minister of the day on the propriety of ministerial appointments. 

When Sunak named Zahawi party chairman and a member of his cabinet, “the usual appointments process was followed,” the premier said in the Commons. “No issues were raised with me when he was appointed to his current role.”

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