Reports have suggest that, as well as the Magpies, Stoke City are interested in the 23-year-old who has failed to score in 13 Bundesliga matches this season.
De Jong has been capped seven times by Netherlands but concedes he has lost faith in Monchengladbach boss Lucien Favre.
Luuk de Jong: "The coach does not give me the impression that he wants to build with me.
"He does not talk to me much. It was a half [season] to forget.
“I can imagine I will leave. The coach will not change much in the second half of the season.
"[I usually played] for three or five minutes. That's no fun. I want to play more"