Gov. Ron DeSantis of Florida woke up in Iowa with a familiar political headache.

The man he is chasing in the polls, Donald J. Trump, had just been disqualified from the ballot in Colorado in yet another legal assault that Mr. Trump leveraged to cast himself as a victim. And so Mr. DeSantis trod carefully the next morning outside Des Moines when he called Mr. Trump a “high-risk” choice, alluding to “all the other issues” — 91 felony counts, four indictments, the Colorado ruling — facing the former president.

“I don’t think it’s fair,” Mr. DeSantis said. “But it’s reality.”

He was talking about Mr. Trump’s predicament. But he could just as easily have been talking about his own.

Boxed in by a base enamored with Mr. Trump that has instinctively rallied to the former president’s defense, Mr. DeSantis has struggled for months to match the hype that followed his landslide 2022 re-election. Now, with the first votes in the Iowa caucuses only weeks away on Jan. 15, Mr. DeSantis has slipped in some polls into third place, behind Nikki Haley, and has had to downsize his once-grand national ambitions to the simple hopes that a strong showing in a single state — Iowa — could vault him back into contention.

For a candidate who talks at length about his own disinterest in “managing America’s decline,” people around Mr. DeSantis are increasingly talking about managing his.