Tompkins was a member of the Kentucky House of Representatives in 1805. He was elected as an Anti-Jacksonian to the Twenty-second and Twenty-third Congresses (March 4, 1831 – March 3, 1835). After leaving Congress, he was again a member of the Kentucky House of Representatives in 1835 and 1836. In addition, he served as a presidential elector on the Whig ticket in 1837. He resumed the practice of law. He died in Glasgow, Kentucky in 1858 and was buried in the family burying ground at Glasgow, Kentucky.