That's what happens when you elect a fragile narcissist

The WAPO sums it up:

Trump has shown time and again that he cares way more about his supporters and his good standing with them than he does about the Republican Party. That has made him an impossible negotiating partner.

When it seemed as if Trump might cave, the right-wing media piled on. Ann Coulter called him “gutless,” and Breitbart News noted Trump’s walk-back of promises from the 2016 campaign (like the fact that “the big, beautiful wall” is now concrete slats). Moreover, Trump’s loyal foot soldiers on Capitol Hill are urging him to reject the spending deal, warning of the major damage it would cause Trump with his base and his 2020 reelection bid. In fact, the leaders of the Freedom Caucus are going to the White House on Thursday afternoon to deliver that message.

Adoration from his base is Trump’s lifeblood. The threat of losing his supporters' affection is enough to make him throw the rest of the GOP and the federal government under the bus. As soon as he started getting criticized by them, he yearned to appease them.

A similar dynamic played out over immigration earlier this year when Schumer offered Trump a deal: funding for his border wall in exchange for a path to citizenship for “dreamers,” the undocumented immigrants brought to America as children. Schumer believed Trump was on board, but as soon as Trump received pushback from his supporters, he turned down the deal.

Which, in a way, is how we got here. Trump never sticks with one line of thinking. His positions are constantly shifting, and he doesn’t provide any lawmakers on Capitol Hill any guidance of where his head is at any moment. The Senate passed a short-term funding bill Wednesday night believing he would sign it and woke up the next morning to find out he wouldn’t.