Levin is all over this. It's crystal clear to him (for a variety of reasons if you stop to think about it a bit) this is a set-up. Democrats are hoping against hope Trump will fire Rosenstein before the election, thus assuring a huge Democrat win which, with control of the House, the first order of business will be Trump's impeachment for obstruction.
If Trump wants to fire Rosenstein (and there are myriad reasons to do so), do it after the election.
Personally, I think Trump and his legal team are far too clever to fall for this.