- The Hundred Days construct is artificial -- but many will view Trump through its lens
- Unexpected events have a way of changing a president's agenda
Julian Zelizer is a professor of history and public affairs at Princeton University and a New America fellow. He is the author of "Jimmy Carter" and "The Fierce Urgency of Now: Lyndon Johnson, Congress, and the Battle for the Great Society." He also is the co-host of the podcast "Politics & Polls." The opinions expressed in this commentary are his own.
(CNN)The clock is ticking. President Trump has between now and April 29 to make the most of his Hundred Days.