(Bloomberg) -- UK Prime Minister Rishi Sunak spent seven months trying to persuade the public that he could put the turmoil of the Brexit years and the pandemic behind him. Now, some in the ruling Conservative Party fear their leader has allowed chaos to return and torpedoed his own salvage job.

Sunak’s dramatic decision to take the official Covid-19 inquiry to court rather than release unredacted versions of Boris Johnson’s WhatsApp messages and personal diaries has raised uncomfortable questions about what Sunak — who was Chancellor of the Exchequer during the pandemic — is trying to hide.

It has thrust the government’s handling of the Covid-19 outbreak back onto the front pages, threatening Sunak’s bid to draw a line between his premiership and the controversies of the past. Perhaps even more frustratingly for Sunak, it has seen Johnson start to re-emerge on the political landscape, after a period in which Sunak had largely managed to keep his predecessor and rival quiet.

In their escalating spat, Johnson on Friday landed a potentially damaging blow when he promised the inquiry he would provide copies of his Covid-era communications — a move that bypasses the government and undercuts Sunak’s attempt to use a judicial review to keep them secret.

The move came with a key caveat: Johnson’s communications from before May 2021 are on a phone locked for security reasons, meaning files from the first year of the pandemic — when the government was widely accused of missteps — may not actually see the light of day. 

Even so, Johnson’s intervention could mark a turning point for Sunak, not only in his standoff with the Covid inquiry, but also his control of the party.

“Every day that Boris Johnson is in the news reinforces a growing perception, even among his fans in the electorate, that he just isn’t strong enough to see off the former prime minister and that this continues to be the Boris show,” said Luke Tryl, a former Conservative government adviser who is now the UK director of the More In Common think tank.

Sunak’s problems may get even worse. On top of Johnson’s communications, the inquiry is trying to track down two WhatsApp groups it says were undeclared and include the government’s top scientific advisers and senior Cabinet Office and Treasury officials discussing pandemic decisions, people familiar with the matter told Bloomberg.

One group comprised Cabinet Secretary Simon Case, Chief Scientific Adviser Patrick Vallance, Chief Medical Officer Chris Whitty and other senior Cabinet Office officials, the people said, and the other included Vallance, Whitty and other senior civil servants in the Cabinet Office and Treasury, as well as permanent secretaries of other government departments.

The groups were where much Covid policy was deliberated and provided space for officials to air their views candidly, away from formal meetings with ministers, the people said. The inquiry believes it has some of the messages, but is investigating whether it has been given the full picture.

The Cabinet Office declined to comment on the WhatsApp groups. It referred to its application for a judicial review, in which it said it is committed to transparency and would hand over all material regards as relevant.

The government has repeatedly said its stance is based on principle, and that public inquiries shouldn’t have the right to demand access to personal communications that aren’t relevant to the subject of their investigations.

An ally of Sunak also said on condition of anonymity that the prime minister has nothing to hide in his WhatsApp communications, and doesn’t use the platform regularly to discuss government business.

Yet the inquiry’s push for the communications underscores the trust issues at stake, when government officials are allowed to determine the relevance of material to a public probe. Even if Sunak himself doesn’t discuss policy via WhatsApp, his officials might — as well as members of other departments.

“If it’s being used for substantive discussions on government policy then the messages should be treated like any other form of government information,” said Tim Durrant at the Institute for Government think tank. “It should be for the inquiry to assess the relevance of these messages to its work.”

According to one government official, the inquiry will inevitably investigate the impact of Sunak’s opposition to pandemic restrictions, as well as his signature Eat Out to Help Out program designed to boost restaurants, but blamed by some scientists for helping to spread the virus. There could also be personal remarks in WhatsApp messages that ministers and officials would prefer to remain out of the public eye, the official said.

And while the probe won’t report its findings until after the election due by January 2025, public hearings ahead of the vote could result in leaks or damaging revelations, one minister warned.

Sunak’s Tories currently trail the Labour opposition by about 16 percentage points in the latest surveys, and the government faces a major task to deliver on its pledges including to cut inflation and boost the economy.

Another official said ministers are concerned by the tenacity with which Heather Hallet, the retired judge selected by Johnson to lend credibility to the inquiry, has shown. While the expectation was for her to be thorough, she appeared determined to embarrass the government, the official said. 

But that reveals the perception issue facing the Tories and Sunak, who has effectively gone to war with an inquiry the government set up itself. The prime minister, like Johnson, was fined by the police for breaking the pandemic rules they helped to write, and the party’s popularity plunged in the fallout.

Rivka Gottlieb, spokesperson for the Covid-19 Bereaved Families for Justice group, said it would be “utterly obscene” if the government didn’t share the messages in full, warning that people will inevitably conclude it wanted to “cover them up” if it didn’t.

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