Sir Keir Starmer's National Security Adviser is thought to be weighing up plans to leave Downing Street in yet another blow for the beleaguered Prime Minister.
Jonathan Powell, credited as the architect of the deal to cede sovereignty of the Chagos Islands to Mauritius, could exit his role by the end of the year.
If Mr Powell should leave, it would mark the fourth blow to Sir Keir following the departures of his Chief of Staff Morgan McSweeney, Cabinet Secretary Sir Chris Wormald, and communications chief Tim Allan in the wake of the Mandelson scandal.
The revelation comes just days after it was reported Mr Powell had turned down offers to take over as the Prime Minister's chief of staff following Mr McSweeney's resignation.
TRENDING
Stories
Videos
Your Say
Sources close to Mr Powell indicate he has little appetite to return to a position he previously held under Tony Blair from 1997 to 2007.
He is said to be contemplating a return to the mediation consultancy he established in 2011.
However, Downing Street officials have firmly dismissed Mr Powell intents to step down from his current role as NSA.
Officials also disputed claims that he was offered the chief of staff position.
Jonathan Powell is said to be considering leaving No10
|PA
The potential departure would mark another significant loss from the Prime Minister's senior team as Mr Powell provided strong counsel to Sir Keir against selecting Lord Mandelson for the role of British ambassador to Washington.
This advice stemmed from his direct experience working alongside Lord Mandelson during the Blair years.
During his time as Mr Blair's chief of staff, Mr Powell was required to manage two separate cabinet resignations involving Lord Mandelson.
He believed Lord Mandelson failed to navigate these controversies effectively on both occasions.
LATEST DEVELOPMENTS:
Recent reports suggest Mr Powell turned down offers to take over as the Prime Minister's chief of staff following Morgan McSweeney's resignation
|PA
Mr Powell's concerns centred on Lord Mandelson's tendency to attract controversy, which he felt would create difficulties for the Prime Minister.
His opposition had nothing to do with Lord Mandelson's connections to Jeffrey Epstein.
The recommendation could surface in internal Government documents scheduled for release following a recent Commons vote.
Mr Powell has been widely viewed as an effective National Security Adviser during his tenure at No10.
Mr Powell currently serves as Sir Keir Starmer's National Security Adviser
|PA
He has served as a crucial link between Downing Street and the European "coalition of the willing" supporting Ukraine.
His efforts to foster Sir Keir's relationship with Donald Trump have been considered amongst the more successful aspects of the Prime Minister's time in office.
He has positioned Sir Keir as a bridge between the United States and Europe.
However, Mr Powell has been central to the contentious Chagos Islands agreement to transfer sovereignty to Mauritius, which sparked political controversy when it emerged Britain would pay £35billion over 99 years to lease back Diego Garcia, which houses a military base.
Mr Powell also facilitated Sir Keir's improved relations with China, culminating in last month's Prime Ministerial visit.
More From GB News