In 1841 he was nominated for U.S. Senator by the Whig caucus in the Tennessee General Assembly. However, some of the Democrats in the legislature decided that no Senator would be preferable to a Whig. Known as the "Immortal Thirteen" by Tennessee Democrats, they refused to allow a quorum on the issue. By the time Jarnagin was eventually elected to the seat and sworn in, over two and half years, almost half of the term, had elapsed. Jarnagin finally assumed office on October 17, 1843 and served until March 3, 1847. During this time, he served as the Chairman of the Committee on Revolutionary Claims. The Whigs nominated him for a second term in 1847, but he was not elected, apparently the Democrats being more amenable to John Bell, another Whig who was eventually elected his successor; a subsequent campaign by Jarnagin for the Tennessee Supreme Court was likewise unsuccessful. Jarnagin moved to Memphis and continued his practice of law there. Jarnagin died from cholera at 1 A.M. on the morning of June 25, 1851 in Memphis.[1][2] He was interred in that city's Elmwood Cemetery.
