Trump may be able to whip his own Republican coalition into shape if he can master the bully pulpit of the presidency. Certainly the fear he struck into his rivals in the Republican primary worked in his favor. He has talk radio on his side, along with Fox News and the Drudge Report. But right now he is still struggling to appoint lower level positions in his Cabinet. He has barely even taken possession of the executive branch. And the traditional measures of popularity show that Trump is not to be feared at all. Politicians act on polls and none of the polls right now say to get on the Trump train. His presidency is already stuck, and Trump himself no longer gets the benefit of being the alternative to the fantastically-detested Hillary Clinton.
So Trump’s first priority tomorrow must be to repair his approval ratings with the public and rally popular support to items on his agenda. And to do that, he has to look beyond his base. His audience in Congress, for instance, is unlikely to appreciate the ad-libbing, stream-of-consciousness style that works for Trump at rallies.
One side effect of Congress kicking so much of its responsibility to the executive branch is that Congress has trouble functioning at all if the president is unpopular. If Trump wants anything to happen for his agenda, he has to capture a popular mandate. Considering that he is a popular vote loser, that the press loathes him, and that a significant sliver of the population thinks he is a fascist in all but name, that’s not an easy task.