it's kinda ironic to see trump trying to unite the party for entirely selfish reasons, having divided it for entirely selfish reasons previously.
i don't think he can do it. the party's grandees have come out, as it were, against trump - so there's no easy way for them to turn back. they see him as destroying their (indicating a possessive sense of the republican) party. and maybe they see him as too destructive of the administrative apparatus of the us ... even for the gop.
i think trump implies a party civil war which splits the gop between ideological small government conservatives and nationalist tea partiers/ southern white supremacists. not sure where the smaller groups of libertarian and north-eastern pragmatists will end up. or the christian block, which may also split up. never been sure how you interpret jesus to mean self-centred, property-loving economics in the first place.
and of course, the protesters represent another group that he is making angry.