Originally a member of the Federalist Party, James Buchanan joined the Democratic party and allied himself with Andrew Jackson after the collapse of the Federalist Party in 1828. He then became an important leader amongst the Democrats in Congress due mainly to his loyalty. He briefly served as minister to Russia and then returned to the United States and was elected to the Senate in 1834.

A native of Pennsylvania, Buchanan helped James K. Polk carry his home state in the election of 1844. For his work he was appointed secretary of state. During his time in the position he pushed strongly for the U.S. acquisition of Cuba, which failed.

Buchanan ran for president in 1848 and 1852 and was unsuccessful. In 1853, he accepted an appointment by president Franklin Pierce as minister to Great Britain. Because of the appointment, he was out of the country during the controversy of the Kansas-Nebraska Act, which helped him to secure the Democratic presidential bid in 1856.

After becoming president in 1856, Buchanan's presidency became known for controversy and corruption. A strong supporter of the southern viewpoint that slavery could not be prohibited by legislation, he engaged in private deals that weakened the Democratic party. He pushed a northern justice of the Supreme Court to vote with southern justices against the Missouri Compromise's legality resulting in the Dred Scott decision, opposed northern-sponsored economic legislation and pushed for an expansionist foreign policy. His most famous misstep was supporting Kansas' admission as a slave state, which went against his earlier pledge to support a fair vote on the issue.

Secession began as a crisis during the Buchanan administration. Seeking to avoid a war, Buchanan refused to recognize secession as a legal act and would not surrender federal property in the south. The majority of his cabinet resigned and was replaced by strong Unionists. Resigned to failure, Buchanan signed informal agreements to appease tensions and was said to be glad to turn over the presidency to Abraham Lincoln when the Republican party easily triumphed in the election of 1860.

Throughout Buchanan's presidency there were rumors that he was a homosexual. While there is no concrete proof, the facts are pretty striking. Buchanan remained a bachelor his whole life, and for many years in Washington he lived with William Rufus King, a Senator from Alabama who later became vice-president under Franklin Pierce. King was also never married.

They spent so much time together many Washington circles referred to them as "the Siamese twins," Andrew Jackson called King "Miss Nancy," and James K. Polk named him "Mrs. James Buchanan."

King himself penned long and intimate letters to Buchanan. When appointed minister to France, King wrote to Buchanan, "I am selfish enough to hope you will not be able to procure an associate who will cause you to feel no regret at our separation." Buchanan later referred to King as "among the best, purest, and most consistent public men I have ever known, and is also a sound judging and discreet fellow," as well as a "very gay, elegant looking fellow."