Is Gingrich advising Trump not to debate Cruz?

I just heard a caller to the Mark Levin radio show allege that Newt Gingrich is advising Donald Trump not to debate Ted Cruz. Mark Levin seemed to agree that Gingrich is doing that, because Levin responded to the caller by saying, "Yeah, c'mon out Newt, expose yourself, baby!" Does anyone know if this is true that Gingrich is advising Trump not to debate Cruz?