Trump is a huge supporter of Hillary Clinton. Take what you want from the fact that (1) the race he jumps into is the best Republican field since 1980, after some absurdly weak fields, (2) he’s positioning himself to draw support from everyone but Bush, (3) Bush is the only candidate likely to lose to Clinton.
He’s called Bill Clinton the best president in his lifetime. I agree entirely with this prediction by Hot Air columnist Allahpundit:
“Heres the easiest prediction of the election, dedicated to everyone who thinks Trumps days of boosting Hillary are behind him. Hell spend the next six months tearing down the most credible candidates in the GOP field, and then, when he eventually drops out of the race, hell reserve his harshest criticism during next years general-election campaign for the GOP nominee rather than Hillary.”