The Magpies have been linked with a £5million move for Alli in the closing days of the January window.
But both Aston Villa and Tottenham Hotspur have now emerged as rivals to sign the 18-year-old.
All interested clubs will be required to loan Alli back to MK Dons.
When asked about his destination on deadline day, MK Dons boss Karl Robinson said: “We just don’t know because there are so many permutations of that.
“It’s not how we do our business and we have to make sure that we do right by him.
“He’s in the midst of all his talk and for him to keep to his level of football with all the hype around him shows you how much of a unique individual he is and he deserves all the success that we know he’s going to get.”