In General Conference, Ezra Taft Benson teaches that Joseph Smith was told by the Lord that the Constitution would one day "hang, as it were, by a thread."
Ezra Taft Benson, Conference Report (Salt Lake City: The Church of Jesus Christ of Latter-day Saints, 1961): 70
In connection with attack on the United States, the Lord told the Prophet Joseph Smith there would be an attempt to overthrow the country by destroying the Constitution. Joseph Smith predicted that the time would come when the Constitution would hang, as it were, by a thread, and at that time "this people will step forth and save it from the threatened destruction" (Journal History, Brigham Young's Speech, July 4, 1854.)