He was chairman of the Republican national executive campaign committee in 1888, and was a member of the United States Senate in1887-1899and again in 1901-1904.
His earliest championship of protection was a resolution introduced by him in the Kentucky legislature (1808) which favoured the wearing by its members of home-made clothes; and one in the United States Senate (April 1810), on behalf of home-grown and home-made supplies for the United States navy, but only to the point of making the nation independent of foreign supply.
In 1790 he was elected to the United States senate to fill the vacancy caused by the death of William Grayson, and although in this body he vigorously opposed Washington's administration, Washington on the 27th of May 1 794 nominated him as minister to France.
In 1845 he declined the Democratic nomination for governor, and also an appointment to the seat in the United States Senate made vacant by the resignation of Judge Levi Woodbury.
Early in 1864, when it became evident that two more Republican votes might be needed in the United States Senate for reconstruction purposes, party leaders at Washington urged the people of Nevada to adopt a constitution and enter the Union as a patriotic duty, and on the 21st of March 1864 Congress passed an act to enable the people of the Territory to form a state government.
He was a Democratic member of the United States Senate from December 1834 until March 1845, ardently supporting President Jackson, and was secretary of state in the cabinet of President Polk from 1845 to 1849 - a period marked by the annexation of Texas, the Mexican War, and negotiations with Great Britain relative to the Oregon question.
The New Hampshire Patriot, founded here in 1808 (and for twenty years edited) by Isaac Hill (1788-1851), who was a member of the United States Senate in 1831-1836, and governor of New Hampshire in 1836-1839, became one of the leading exponents of Jacksonian Democracy in New England.
He was president of New Hampshire in1785-1786and in 1788-1789; a member of the Federal Constitutional Convention in 1787, where he voted against granting to Congress the power of issuing paper money; a member of the state convention which ratified the Federal Constitution for New Hampshire; a member of the United States Senate in 178 9 -1801, and its president pro tem.
In the meantime the United States Senate had appointed a committee to inquire into Georgia's claim to the land in question, and as this committee pronounced that claim invalid, Congress in 1800 established a Territorial government over the region.
He returned to New York in 1798, resumed the practice of his profession, re-entered politics, and sat in the United States Senate as a Federalist from 1800 to 1803.