A history of same-party challengers

John Tyler, who had taken over as president after William Harrison's untimely death, was expelled from the Whig Party thanks in part to his veto of a few banking bills. When it was time for reelection, the Whigs nominated Henry Clay in his place—though Tyler's followers intended for him to run as a third party.

Millard Fillmore may be partially responsible for starting the Civil War during his time as president. The Compromise of 1850 tore his party, the Whigs, in half: The northerners sought to end slavery, and the southerners supported it. Fillmore did seek reelection at the last minute, but the controversial set of bills lost him support within the party. The Whigs then named Winfield Scott as their candidate.

Some consider Bleeding Kansas a small Civil War; others consider it the reason President Franklin Pierce was booted from the primary in favor of James Buchanan. Buchanan had no part in this controversy, unlike Pierce who was embroiled in the issues in Kansas. Pierce and another candidate, Stephen Douglas, joined forces to try and block Buchanan. Douglas eventually pulled out of the race, paving Buchanan's path to the presidency.

Andrew Johnson, who took on the role of president following Abraham Lincoln's assassination in 1865, was the first president in history to be impeached. Impeachment proceedings followed the volatile conclusion of the Civil War, and included 11 articles voted on by the U.S. House of Representatives—nine of which centered on Johnson's removal of Secretary of War Edwin M. Stanton, which was in violation of the Tenure of Office Act that congress passed over his veto in 1867. Johnson was impeached in 1868 and shunned by his entire party, giving Horatio Seymour an opening through which to secure the Democratic primary nomination. Seymour lost in the general election that year to Ulysses S. Grant.

The Republican Party was severely divided in 1884, a problem that hit President Chester Arthur hard. Arthur wanted to run for reelection, but couldn't unify the different groups within the party. James Blaine could, however, thanks to his persistence and strong political background. Blaine was narrowly bested in the election by Democratic New York Gov. Grover Cleveland, marking the first Democrat elected to the presidency since 1856—a full six years before the start of the Civil War.

President William Taft essentially turned his back on Theodore Roosevelt after Taft secured the presidency in 1908. Roosevelt had worked tirelessly to groom Taft for the position but found his mentorship all but abandoned by Taft. Furious, Roosevelt ran against Taft in the 1912 presidential primary, effectively creating the Progressive Party and running on that ticket. The rift created a divided Republican electorate, which resulted in Democrat Woodrow Wilson securing the presidency. 

The country seemed idyllic in the early 1950s for a large swath of the American public. People had a perceived notion of safety, and major crimes were extremely uncommon—that is, until Estes Kefauver arrived. Kefauver led a criminal investigation across the entire country, rounding up anyone and everyone perceived to have broken the law. This push increased his popularity so much that he ran for the Democratic Party's presidential nomination. Kefauver secured a landmark victory in New Hampshire's primary, which prompted Truman to withdraw his re-election bid. Kefauver eventually lost the primary bid to Illinois Gov. Adlai Stevenson, who in turn lost in a landslide to Republican Dwight D. Eisenhower.

The Vietnam War made 1968 an incredibly tough year for politics. President Lyndon Johnson made several unpopular policies relating to the war, which led Sen. Eugene McCarthy of Minnesota to run against him—and perform very well. It was soon discovered that McCarthy's popularity wasn't necessarily because people liked his anti-war stance; they just didn't like Johnson, who withdrew from the election when McCarthy scored 42% of the primary vote in New Hampshire and Sen. Robert F. Kennedy jumped into the race. With Johnson no longer in the game, Vice President Hubert H. Humphrey threw his hat into the Democratic ring and bested McCarthy—only to lose in the general election to former Vice President Richard Nixon.

The war continued in 1972, and Pete McCloskey found himself at odds with the Republican Party for being staunchly anti-war. His stance led to him running against Richard Nixon in the primaries. McCloskey ran as a peace-seeking alternative, but ultimately failed. Nixon received an astounding 521 electoral college votes to McCloskey's 17 and 49 states (all but Massachusetts and the District of Columbia) in one of the largest political landslides in American history.

Five years before Ronald Reagan became president, he set his sights on President Gerald Ford, aiming to finally win the Republican nomination following six straight losses in the primaries. Reagan nearly succeeded, even with a GOP that couldn't pin down exactly why he was so popular. Reagan attacked Ford's foreign policy and spending, and Americans responded positively, viewing him as uncorrupted. Still, Ford won—only to lose to Democrat Jimmy Carter of Georgia.

The late 1970s came with a complex set of problems that included high inflation, hostages in Iran, rising unemployment, riots, and an energy crisis. In 1980, Democrat Ted Kennedy took up the reins to challenge President Jimmy Carter—a move which deeply divided the Democratic Party. Kennedy's natural charisma, combined with a drop in confidence after Carter fired his entire cabinet, gave Kennedy a leg up in the fight, but ultimately Carter secured the nomination. He went on to lose to Ronald Reagan in the general election. 

When Buchanan challenged then-President Bush, the Republican party was beginning to fracture. The era of Reagan and communism was over, and conservatives were in-fighting over the direction of the party. Though he ultimately lost, Buchanan gained quick support by calling attention to the GOP's problems, announcing he would change the party's direction entirely. Many simply considered Buchanan to be a less-dangerous alternative, although ultimately the electorate swung Democratic and elected Arkansas Gov. Bill Clinton to the presidency.