Answer:
The acceptance of the Lecompton Constitution by President Buchanan set off a firestorm within the Democratic Party, resulting in its split.
Explanation:
The Lecompton Constitution of 1857 was to make the Territory of Kansas, created three years earlier in the city of Lecompton, a slave state. The text also aimed to give greater legal force to slavery by banning any interference in this area by the federal state and the capital Washington.
Highly contested, four years before the American Civil War, this draft constitution made the following statements:
-The right of ownership precedes and is superior to any constitutional sanction, and the right of the owner of a slave over his slave ... is identical and just as inviolable as the right of the owner of any other property.
-No law shall emancipate slaves without the consent of their owner, nor without paying the owners full compensation in money for the value of slaves so emancipated. Immigrants in the state may not be prohibited from bringing with them persons held for slavery by the laws of any state or territory of the United States from [...] the time that they actually own them [ ...]
According to these principles, the law of Illinois freeing slaves present on its territory violated the fundamental rights of the citizens of Missouri, and the principles of courtesy between states were naturally defeated in the defense of these rights.
At the same time, a judgment of the United States Supreme Court in March 1857 called Scott v. Sandford took a strong position in favor of slavery, declaring, on the one hand, that a black man, even a free man, could not be a citizen of the United States, on the other hand that, in the territories of the United States which, at the time, were not yet states and were administered by the federal government, the latter could not prohibit slavery.
Debates around the constitution, and beyond, about slavery in the territory provoked between 1854 and 1858 a succession of violence announcing the Civil War, called Bleeding Kansas.
After a first referendum favorable to the project, but contested for fraud, the voters of Kansas rejected massively the proposal of the Lecompton Constitution by a vote of 226 votes against 138 (the partisans of the slavery had boycotted this referendum). And in Washington, the Lecompton constitution had been rejected by the House of Representatives in 1858 for frauds, many of the northern Democrats voting with the Republican Party against the Southern Democrats, pro-constitution.
Kansas was admitted to the Union as a free state in 1861 as the Civil War began.
