It would not be a debate. It would be a discussion on a call in radio show where Levin would have 2 guests.
I am pretty resigned to Trump winning this thing, but honestly if Mark Levin was to challenge both of these candidates, Trump would lose big in the discussion and he knows it.
The fact that Trump is ready to sit out a debate tells me he is perhaps a bit overconfident. He will probably get about a third of the Iowa Delgates. Cruz will get 20-25% and the also rans will get the rest. A big win in Iowa really means nothing.
It will bring in more listeners to Mark’s show.