Joseph Smith’s journal mentions his advocacy of US Constitution, finds fault in its broadness.

Date: Oct 15, 1843
Type: Personal Journal / Diary
Source: Willard Richards
LDS
Hearsay: Scribed Verbatim
Direct
Reference: Journal entry for 15 October 1843, December 1842–June 1844; Book 3, 15 July 1843–29 February 1844, p. 128
Scribe/Publisher: Willard Richards
People: Joseph Smith, Sr., Joseph Smith, Jr., Willard Richards, Parley P. Pratt
Audience: N/A
Transcription: Sunday Oct 15. 1843. 11 A.M. cool. calm. cloudy.
stand east end of the temple. singing Prayer By. P[arley] P. Pratt. Joseph— preached.
It is one of the first principles of my life. & one that I have cultivated from my childhood. having been taught it of my father. to allow eve[r]y one the libe[r]ty of conscience. I am the greatest advocate of the C[onstitution] of U.S. there is there on the earth. in my feeling <the> only fault I can find with it is it is not broad enough to cover the whole ground.
Source Link: https://www.josephsmithpapers.org/paper-summary/journal-december-1842-june-1844-book-3-15-july-1843-29-february-1844/134
Citations in Mormonr Qnas: Joseph Smith's Presidential Campaign