 He served a register of probate for the district of Bradford from 1842 to 1846, and probate judge from 1847 to 1849.He was a Democrat until the outbreak of the American Civil War, an alternate to the Democratic national convention of 1848, delegate for the next three conventions, in 1852, 1856 and 1860, and candidate for Lieutenant Governor in 1860.Governor Erastus Fairbanks called an extra session of the State Legislature on April 23, 1861, which Thomas attended.