The Democrats are riven and falling apart. With Trump gaining in the polls and Hillary's likability sinking like a rock, they know their only hope is to keep the GOP splintered while they desperately try to re-form. The bad news for Dems is that Republican voters are rallying behind Trump (willingly) the same way they (unwillingly) rallied behind Romney and McCain. The bad news is that the GOP establishment is, and always has been, the weak link.
Between cutting deals to try to hang on to their jobs in a Hillary administration they'll welcome aboard and outright cowardice and incompetence the GOP "elite" is more fractured than ever. Trump has made allies of enemies (Perry, Carson, and most of all Chris Christie)--but even so he has a ways to go.
The issue, of course, is the "Raaaaacist" tag that they are so cowed by. Racism has become an "invisible disease." You can't say what it is (or isn't)--anything can be racist--and any 'hint' of racism is enough to kill you. It "catches" from one person to another. In fact, to hear Mitt Romney say it, racism can now actually "trickle down" somehow. It's like a new plague.
Get endorsed by the KKK? Unless you stop-drop-and-roll the "racism" will stick. Have guys online say good things about you? They'd better be sterilized or else your Twitter Feed could contract the deadly Racism Disease. And if you've got it? The only cure is to grovel and call other people racist too (if you have ever seen a feminist workshop, you can see this in action when people walk through the door: it's like a quick-draw contest to call someone else racist, sexist, ableist, or whatever the term-de-jour is).
That is, unless you're Trump. If you have a backbone you say what you meant and stick to it. It's too bad we have so few politicians who will even attempt to stand up to this tactic. Good thing that's all going away in November.