Keir Starmer is reportedly mulling hiring the chief Partygate investigator Sue Gray as his chief-of-staff.
The senior civil servant, who authored a bombshell report into lockdown-busting parties in No10, became a household name during the scandal that rocked Boris Johnson's Government.
Ms Gray currently works as the Second Permanent Secretary at the Cabinet Office - a department she has worked in since the 1990s - has built a formidable reputation in Whitehall.
The Labour leader is said to be considering her for the vacant role of chief-of-staff.
A Labour source told Sky News: "[Sue Gray] knows how Number 10 works and she's very popular with civil servants".
A party spokeswoman did not deny the report, only saying: "The process is ongoing, nobody has been offered the job".
But it is understood Rishi Sunak could theoretically block any such appointment.
Rules governing senior civil servants' appointments state that an application is required for a two-year period after leaving office.
It must be referred to the Advisory Committee on Business Appointments (ACOBA) - an official watchdog which provides advice to the Prime Minister.
It makes clear the PM "makes the final decision".
Due to senior civil servants' access to a range of sensitive information, the rules add: "All Permanent Secretaries, including Second Permanent Secretaries, will be subject to a minimum waiting period of three months between leaving paid Civil Service employment and taking up an outside appointment or employment.
"The Advisory Committee may advise that this minimum waiting period should be waived if, in its judgement, no questions of propriety or public concern arise from the appointment or employment being taken up earlier.
The Cabinet Office has not commented on the report but the Prime Minister's official spokesman said on Thursday Ms Gray was still working in her role.
Asked if she handed in her notice, they added: "I'm not going to be commenting on an individual or that kind of speculation but as I said she is continuing in her role".
Ms Gray's Partygate report - published after the Metropolitan Police issued over 120 fines - tore into "failures of leadership and judgement" in Mr Johnson's Government during the Covid crisis.
Almost six months after The Mirror first reported a breach of Covid rules, the senior civil servant concluded in her report the lockdown-busting events "should not have been allowed to happen".
She said the public "have a right to expect the very highest standards of behaviour in such places and clearly what happened fell well short of this".
