As Donald Trump approaches the 100-day marker of his first year in office, he has defined himself not as the Dealmaker in Chief but as the Backdown President.

What a deliciously strange irony that until Monday night he set the stage for a government shutdown over, of all things, his campaign centerpiece — The Wall.

Strange because Trump, who now calls the faux deadline “ridiculous,” promised so much by his 100th day. Delicious because everything Trump does is scrumptious, especially eating chocolate cake while launching real missiles.

And it was always clear to perennial observers of Washington’s sausage factory that the new president’s ambitions exceeded the pace and will of the nation’s political class. Today’s Republican Party may control the executive and legislative branches, but its members are hardly trilling in harmony, thanks to the too-rare interference of mental clarity.