Prime Minister Rishi Sunak says he will not tell Conservative MPs how to vote on any potential sanctions a committee may recommend for Boris Johnson over his alleged partygate involvement.
Former prime minister Mr Johnson is preparing to face an investigation over claims he lied to Parliament over the scandal about parties and other gatherings of government and Conservative Party staff held during Covid-19 lockdowns.
Mr Johnson will give evidence before a committee on Wednesday, in a session that could determine his political future.
If he is found in contempt of Parliament, Mr Johnson could be suspended from the House of Commons and even face a recall petition, which could lead to a by-election, giving his constituents in Uxbridge and South Ruislip the chance to remove him.
However, Mr Sunak has said he will not instruct MPs on how to vote on any sanctions the committee may recommend.
The Prime Minister told BBC Breakfast: "These are matters for Parliament and the house and MPs as individuals, rather than for government. So that is the general process that we will follow."
Asked whether he agreed with the portrayal of the inquiry as a witch hunt by some of Mr Johnson's associates, Mr Sunak said: "That's ultimately something for Boris Johnson and he'll have the committee process to go through and that's a matter for Parliament. That's not what I'm focused on."
Mr Johnson is facing a wait for the publication of his defence to allegations he lied, which allies claim will provide evidence that he did not mislead Parliament knowingly.
The former prime minister's allies urged the cross-party Privileges Committee to publish his testimony "as soon as possible" after turning it over on Monday afternoon.
But clerks and lawyers are still combing through the lengthy document.
Mr Johnson was asked to provide a written submission in July last year but submitted it only 48 hours before his televised questioning by the committee on Wednesday afternoon.
The committee confirmed it had received the evidence, key to Mr Johnson's political future, at 2.32pm on Monday.
Conor Burns, a Tory MP who served as a minister in Mr Johnson's government, has raised questions about the committee's chairwoman, Labour grandee Harriet Harman, while Conservative peer Lord Greenhalgh backed a campaign for the four Conservative MPs on the Tory-majority committee to pull out of the "kangaroo court".
Mr Burns, a long-standing ally of Mr Johnson, who served under him at Westminster and London City Hall, told Times Radio: "I'm concerned that it will be a witch hunt."
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The Prime Minister's official spokesman responded by saying Mr Sunak "firmly believes it's a matter for Parliament".
He endorsed Commons Leader Penny Mordaunt's warning that "a very dim view will be taken" of anyone who "tries to prevent them from carrying out this serious work".
She also said the committee must be able to "work without fear or favour".
Mr Sunak's spokesman added: "We think this is a committee that's carrying out a function asked to by Parliament, it's a parliamentary matter, and the Leader of the House set out how we would want parliamentarians to engage with it."
No 10 Downing Street was also forced to deny it had delayed key announcements because of the distraction of Mr Johnson's inquiry.
"It's wrong to suggest government business changes as a result of this committee hearing," the spokesman said.
The hearing clashes with a crucial vote on Mr Sunak's new Brexit deal for Northern Ireland, which Democratic Unionist Party MPs plan to oppose.
An estimated £220,000 ($269,390) of taxpayers' money has been allocated for Mr Johnson's legal bills.
If the committee rules that he misled the house, they will consider whether it was "reckless or intentional" and amounted to a contempt of Parliament.
An interim report by the committee this month said evidence strongly suggested breaches of coronavirus rules would have been "obvious" to him, as prime minister at the time.
But Mr Johnson claimed it was "clear" he had not committed any contempt of Parliament, arguing there was "no evidence in the report that I knowingly or recklessly misled Parliament" or failed to update it in a timely manner.
Mr Johnson has also sought to cast doubt on the findings of Sue Gray's report on partygate, after she quit the civil service to take up a role in Labour leader Keir Starmer's office.
On BBC Radio 4's Westminster Hour, Mr Burns said: "I rate Harriet Harman highly, but she did tweet in April 2022 that if [Mr Johnson and Mr Sunak] admit guilt, by which she said was accepting a fixed penalty notice, then they are also admitting that they misled the House of Commons.
"Boris Johnson contests that but it seems to me the person who is chairing this committee has predetermined it and that causes me a degree of anxiety for Parliament's reputation in handling this with integrity."
The Privileges Committee is examining evidence around at least four occasions when Mr Johnson may have misled MPs with his assurances to the Commons that lockdown rules were followed.
The committee will publish its findings on whether Mr Johnson committed a contempt of Parliament and make a recommendation on any punishment but the ultimate decision will fall to the full House of Commons.
Mr Sunak has said he will not seek to influence MPs on the committee and is expected to grant a free vote in the Commons on any sanction that may be recommended.
A suspension of 10 sitting days or more for Mr Johnson could ultimately trigger a by-election in his Uxbridge and South Ruislip seat in London, which he held with a majority of 7,210 in 2019.
