A
Democrat, he became active in politics as a campaign speaker on behalf of Andrew Jackson in 1828. In 1838, he won election to the
Louisiana State Senate from
Catahoula,
Ouachita and
Union Parishes, and he was reelected in 1842. A longtime member of the Louisiana Militia, in 1842 Downs was appointed
brigadier general of the organization's 6th Division. In 1844 he was a delegate to the state constitutional convention. Also in 1844, he agreed to run for presidential elector as a supporter of Martin Van Buren. When Van Buren came out against annexing Texas, Downs resigned, but he agreed to run again after
James K. Polk was nominated. Polk won the election and carried Louisiana, and Downs cast his ballot for the ticket of Polk for president and
George M. Dallas for vice president. Downs moved to
New Orleans in 1845. He served as
United States Attorney for the district of Louisiana from 1845 to 1846 and a member of the
State constitutional convention. He was elected as a
Democrat to the U.S. Senate and served from March 4, 1847, to March 3, 1853. While in the Senate he was chairman of the Committee on Engrossed Bills (Thirtieth Congress) and the Committee on Private Land Claims (Thirtieth through Thirty-second Congresses). In the Senate, Downs was an unusually staunch supporter of the institution of slavery, from which he personally profited. "I call upon the opponents of Slavery to prove that the white laborers of the North are as happy, as contented, or as comfortable as the slaves of the South," he said in one speech. "In the South the slaves do not suffer one tenth of the evils endured by the white laborers of the North...This, sir, is one of the excellencies of the system of Slavery, and this the superior condition of the Southern slave over the Northern white laborer." After his term, he was appointed by President
Franklin Pierce as
United States Collector of Customs for the
District of Orleans in 1853 and he served until his death. ==Death and burial==