Goretzka's current deal expires in the summer and he has so far stalled on putting pen to paper on an extension, with some of Europe's biggest clubs thought to be interested in the 22-year-old.
The likes of Manchester United, Barcelona, Liverpool, Arsenal and Bayern Munich are monitoring the situation, and Clemens Tonnies - the chairman of Schalke's supervisory board - has now called on the Germany international to make his decision.
"We've done everything to ensure he stays. In January, he wants to say what he's doing. Schalke have accepted the financial conditions of Leon and his management," Tonnies told Welt am Sonntag
"He was also important for the sporting development of the team last summer and, after the first half of the season, we're in second place and in the quarter-finals of the DFB-Pokal. Leon can and must decide now."
Goretzka has scored four goals in 11 Bundesliga appearances for Schalke this season.