I'd be willing to bet that most FRpeers would not make that pledge. Trump main issue is illegal immigration, how in hell can someone who's main issue is immigration pledge to support a Jeb Bush or any of the other amnesty candidates? Jezz this is not rocket science.
Personally I'm at the point there I think Trump should go third party. Screw the uniparty.
They can't. As much as some Freepers and others want to fit this years critical issues into liberal and conservative, they just won't fit. Legal and illegal immigration, bad trade deals and US sovereignty are more critical this election cycle, and liberal and conservative pols are all over the map on those issues.