Tyler, born to an aristocratic Virginia family, came to national prominence at a time of political upheaval. In the 1820s the nation's only political party, the Democratic-Republicans, split into factions. Though initially a Democrat, his opposition to Andrew Jackson and Martin Van Buren led him to ally with the Whig Party. A native of Virginia, Tyler served as a state legislator, governor, U.S. representative, and U.S. senator before his election to national office in 1840. He was put on the ticket to attract disaffected Southerners.
Harrison's death made Tyler the first vice president to succeed to the presidency without being elected to the office. To forestall a constitutional crisis, Tyler immediately moved into the White House, took the oath of office, and assumed full presidential powers, a precedent that would govern future successions and eventually become codified in the Twenty-fifth Amendment. A strict constructionist, Tyler found much of the Whig platform unconstitutional, and vetoed several of his party's bills. Believing that the president should set policy instead of deferring to Congress, he attempted to bypass the Whig establishment, most notably Kentucky Senator Henry Clay. Most of Tyler's Cabinet resigned soon into his term, and the Whigs, dubbing him His Accidency, expelled him from the party. Although he faced a stalemate on domestic policy, he had several foreign-policy achievements, including the Webster-Ashburton Treaty with Britain and the Treaty of Wanghia with Qing China.
President Tyler dedicated his last two years in office to the annexation of Texas. He initially sought election to a full term, but had lost the support of both Whigs and Democrats, and he withdrew. In the last days of his term, Congress passed the resolution authorizing the Texas annexation, which was carried out by Tyler's successor, James K. Polk. When the American Civil War began in 1861, Tyler sided with the Confederate government, and won election to the Confederate House of Representatives shortly before his death. Although some have praised Tyler's political resolve, his presidency is generally held in low esteem by historians; today he is considered an obscure president, with little presence in the American cultural memory.