During the 1804 election for Governor of New York between Morgan Lewis and Aaron Burr, both Democratic-Republicans, Burr actively courted the support of Federalists. Griswold authored a private letter advocating that Federalists support Burr, arguing that it was the best way to keep the Federalist Party viable for future elections. Griswold's letter was eventually made public, and appeared in an 1807 handbill accusing the Federalists of unseemly political intriguing, to the party's detriment.
He resumed the practice of law in Herkimer, and died there March 1, 1809; interment was in Oak Hill Cemetery.