Donald Trump has moved quickly on his far-reaching agenda, but his administration has frequently changed both its messaging and its course.

The chaotic start of his presidency has been characterized by a rash of reversals and retreats as he hastens to execute his agenda while his party controls both houses of Congress and his political capital is at its peak.

His advisers are well aware of a looming deadline: the midterm congressional elections a year and a half from now. If Republicans lose control of Congress, the Trump presidency could well be over for practical purposes. Democratic majorities would surely block any ambitious legislative initiatives, and, armed with subpoena power, they could paralyze the back half of his presidency through investigative hearings.