Stewart has returned to parent club Hull City following a successful loan stint at The Valley and the Addicks want the 22-year-old back permanently, and they have the finance to do the deal after Belgian millionaire Roland Duchatelet completed his takeover of the club.
However, Sky Sports understands that a number of Championship clubs have now made contact with Hull about a deal for Stewart.
Understood to be among those clubs are promotion candidates Leicester City, Ipswich and Leeds United, who are all keen to add Stewart to their ranks.
Hull boss Steve Bruce has confirmed interest in Stewart, and is set to let him leave, although he could be involved in Saturday's FA Cup tie at Middlesbrough before his departure.
Talking to Sky Sports, Stewart said that he was waiting to see what happens over the coming days.
"I will discuss all the options with my agent and will hopefully be in a position to make a decision on my future in the next few days," he said.