Whatever PDJT has on Flake- and I’m sure it is plenty - should be made clear to Flake now that PDJT will go nuclear on him. I don’t think any of these McCain types have taken PDJT to the edge yet, but it is getting close.
Offer Flake a damned embassador position to some place in Europe or South American if that’s what it takes. That may not be necessary if a small handful of Democrats vote for the nominee. A few are in states that Trump won by multiple digits. Then replace him.