D. Michael Stewart in Ensign writes that Joseph Smith did prophecy Constitution would be imperilled and the Elders would play a role in saving it.
D. Michael Stewart, "I Have a Question: What do we know about the purported statement of Joseph Smith that the Constitution would hang by a thread and that the elders would save it?," Ensign (June 1976), accessed June 28, 2021
The documents show that Joseph Smith did prophesy a number of times that the United States and the Constitution would be imperiled and that the elders would have a hand in saving them.