Slomka's current deal expires next summer but, after leading the club to their two most successful seasons, Hannover are keen on tying him down to a longer deal, especially given the positive signs from the start of the present campaign.
The Reds are currently fifth in the Bundesliga with 11 points, just three behind the top three.
"Our aspirations are the same," said Schmadtke. "That is a foundation to be able to lead successful negotiations and that is what we are doing."
Slomka, who led Schalke to the quarter-finals of the Champions League in 2008, is developing a strong reputation which has also attracted praise from Bayern Munich president Uli Hoeness.
However, Slomka would not use Hannover as a springboard to a better job, saying: "If I extend my contract with Hannover, then I will put my heart and soul into it.
"There would be no alternatives then," he added on Sport1 television.
"Of course it is nice to be liked and rated in the Bundesliga, especially when your work is recognised."