Donald Trump was never a Democrat, just as he was never, and is not now, a Republican.  He has no ideology at all, no political principles, no vision -- except for his vision of himself as the guy in charge, and, of course, WINNING!

Democrats by now have surely recognized that the most advantageous thing for their party is to let this flaming orange Hindenburg crash and burn and leave the Republicans to scramble, flaming, from the fireball.  Two years from now, as the GOP civil war rages, the Dems will take back the House and Senate,  and spend the next two years giving the Republicans a taste of their own medicine.  Which is only fair, if not necessarily good for the country.

That's if Steve Bannon doesn't have Trump assassinated by "radical Muslim extremists" so he can seize power at the point of a gun with the network of acolytes he will have built within the Homeland Security apparatus. 

I'm still betting on that.