The Yorkshire club were set to sign the Wales winger from Swansea 16 months ago before United swooped with a £15million bid.
But with James, 22, already struggling to command a regular starting place - and Ole Gunnar Solskjaer still searching for new wide players - he could be on his way in the current window.
United had hoped to get Gareth Bale on loan - as revealed in the Daily Star Sunday last weekend - only for the Real Madrid star to snub their approach in favour of Tottenham.
However, they are still trying to persuade Borussia Dortmund to sell them England ace Jadon Sancho - for less than the current £108m asking price.
Inter Milan’s Croatian ace Ivan Perisic, 31, is another United target while they have also been linked to Bournemouth playmaker David Brooks.
Should any of those deals happen, James will automatically drop further down the Old Trafford pecking order.
Which would pave the way for Leeds to take him on loan for the season - with an option to make it a permanent transfer next summer.