Unfortunately, I do not know the location of the original issues. The references were extracts from the related Senate Reports and can be found in the U.S. Congressional records (U.S. Serial Sets).

Do you need specific Minden Democrat issues? Is it possible that the information you seek was published in another area newspaper?

I'm sure you have covered most of the options; just listing a few potential resources:
1. The local Minden papers
2. The local Libraries of Webster, Claiborne, Bienville, or Caddo parish (Shreveport) - one possibility
3. LSU Shreveport (Archives and Special Collections)
4. Publishers of Genealogical materials for the area (J & W Enterprises, is just ONE example).
5. One of the local Historical Societies, or the State or Regional Historical Association.