According to the Daily Mail, all three clubs are "watching him closely," though any formal move is understood to depend on departures from within their own defensive ranks first.
Manchester United's interest in Branthwaite is not new. The club held talks over a move as far back as 2024, when two bids for the defender were rejected by Everton.
Those offers came during Erik ten Hag's time in charge at Old Trafford, with Branthwaite having first emerged as a target after a successful loan spell at PSV Eindhoven.
Everton have continued to resist any departure for Branthwaite, who signed a new long-term contract with the club last year that runs until 2030.
That deal is reported to include a release clause in excess of £70million, a figure that reflects the value Everton place on one of the most promising young defenders to emerge from their academy in recent years.
The England international has made just eight appearances this season after a series of injury setbacks, though his underlying profile, including his physical presence and ball-playing ability, continues to attract interest from clubs at the top of the Premier League and beyond.
Reports earlier this year suggested representatives for Branthwaite had reiterated his interest in a move to Manchester United during a meeting in February, even as Everton remained relaxed about his long-term commitment to the club.
For Manchester United, any pursuit of Branthwaite would form part of a broader defensive rebuild.
Harry Maguire's continued presence in the squad gives United some breathing room, but the club is understood to be planning for his eventual successor rather than waiting until his departure becomes urgent.
Everton's £70million valuation represents a significant rise on the figures discussed in 2024, when the Toffees were said to be holding out for around £80million despite United's bids falling well short of that mark.
Whether any of the interested parties are prepared to meet that price this summer remains to be seen, but Branthwaite's situation is likely to be one of the more closely watched defensive sagas of the window.