Boris Johnson could publish his defence documents on Monday as he prepares to face an investigation over claims that he lied to Parliament over the partygate scandal.
Before the former prime minister gives evidence on Wednesday, in a session that could decide his political future, the privileges committee is expected to publish the lengthy submission from Mr Johnson’s barrister, Lord David Pannick, KC.
Allies insist he expects his position to be “vindicated” after submitting a “detailed and compelling” account of his case, with an estimated £220,000 ($268,000) of taxpayers’ money having already been allocated for his legal bills.
The document is said to provide evidence that Mr Johnson did not mislead Parliament knowingly.
He will provide the statement to the committee, which is scheduled to sit from 2pm to 6pm to determine his fate.
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 the chance to remove him.
“I'm sure Boris Johnson will give a robust defence of himself and then it will be for the committee to determine the outcome of it,” the Chancellor of the Duchy of Lancaster, Oliver Dowden, told Sky News on Sunday.
Mr Dowden said a free vote for Conservative MPs if the committee recommends sanctions against Mr Johnson was “the standard practice” on house matters.
“I'm not sure final decisions have been made but that would be the precedent that we would expect to follow,” he said.
In an interim report, the privileges committee said the evidence strongly suggests that breaches of coronavirus rules in No 10 should have been “obvious” to Mr Johnson.
They are examining evidence around at least four occasions when he may have deliberately misled MPs with his assurances to the Commons that rules were followed.
The Sunday Times reported Mr Johnson will tell of previously undisclosed WhatsApp messages from senior civil servants and members of his Downing Street team showing he had relied on their advice when he made his statements to parliament.
He will also publish messages that show other senior figures in Downing Street believed the gatherings were covered by the “workplace exemption” in the lockdown rules.
The committee's investigation is being led by Labour's Harriet Harman, although the seven-strong panel has a Tory majority.
It will publish its findings on whether Mr Johnson was in contempt of Parliament and make a recommendation on any punishment, but the ultimate decision will fall to the full House of Commons.
Prime Minister Rishi Sunak has said he will not try to influence MPs on the committee and indicated he will grant a free vote to Tory MPs on any sanction that may be recommended.
A suspension of 10 sitting days or more for Mr Johnson could ultimately lead to a by-election in his Uxbridge and South Ruislip seat, which he held with a majority of 7,210 in 2019.
On Friday, a Conservative Party representative confirmed Mr Johnson would stand as a candidate again in the constituency, after the Conservative Party re-elected him to the seat he has held since 2015.
There had been recent speculation that the former prime minister might try for a safer seat before the next general election.