Holtby moved to Tottenham from Schalke 12 months ago, but has so far been unable to hold down a regular place in the starting XI.
Holtby played in a variety of positions under Andre Villas-Boas, but has only started one game since Tim Sherwood was installed as head coach and now the German wants to leave.
"My feeling is that he will leave but it's not in our hands at the moment," Holtby's agent Marcus Noack told Press Association Sport.
"Tottenham have to agree to let him go first. We hope to find a solution in the next couple of days."
Any hopes of Holtby securing a move away from Tottenham appear to have been scuppered by the club's valuation of the player.
Although Spurs only paid £1.25million for the player a year ago, Holtby's camp claim the north London club want between £8million and £10million for the 23-year-old.
"I think it will be a loan because it is difficult for anyone to buy Lewis," Noack added.
Borussia Dortmund enquired about Holtby's availability earlier this month, but Press Association Sport understands last year's Champions League finalists have since cooled their interest in the midfielder.
Schalke, where Holtby spent three and a half years before heading to England, are interested in re-signing the German international, but the Bundesliga club may have to sell players - like Arsenal target Julian Draxler - before they can bring any new faces in.
Former Germany defender Christoph Metzelder claimed on Twitter that he had seen Holtby in Dusseldorf - near to where Schalke and Dortmund are based - but Spurs insist the player is in London as he is in the squad for Wednesday's Premier League clash against Manchester City.
Press Association Sport understands Holtby would prefer to stay in England, anyway. Fulham have recently been linked with a temporary move for the midfielder.