Democratic Senator Stephen A. Douglas hoped to become president of the United States. Toward that end, from his powerful position as chairman of the Senate transportation committee he decided to begin to organize the territory to the west of Missouri so as to enable the building of the first transcontinental railroad. He wanted the eastern terminus to be in Illinois in the hope that the benefits to commerce would have the same kind of effect on Chicago that the Erie Canal had on New York. In 1854 he brought forth an act organizing the territories of Kansas and Nebraska on the basis of popular sovereignty.
As a Democrat Douglas was aware that to have any chance of winning the White House, he would need Southern support. Southerners were unhappy with the proposed legislation. They wanted a Southern route for the railroad, and because the Nebraska Territory was north of the Missouri Compromise line, it was off-limits to slavery. Douglas proposed to solve that issue by organizing the territory on the basis of popular sovereignty, so he inserted into the act a provision for the specific repeal of the Missouri Compromise.
When the bill passed, many in the North were outraged by repeal of what was regarded as a sacred pledge—the prohibition of slavery north of the Missouri Compromise line. Passage of the act contributed to the final demise of the Whig party as its members disagreed on whether or not to support the Kansas-Nebraska Act. Many Northern Democrats also left the party because of the Nebraska bill. Some of those anti-Nebraska Democrats migrated to the new Republican Party which formed in 1854. In the congressional elections of that year the Democrats lost heavily in the North and became virtually the only political party in the South.
Although the 1850 Compromise might have delayed the inevitable slide towards secession and war, Douglas's Kansas-Nebraska Act of 1854 very likely speeded up the process. Douglas's biographers point out that although he was personally opposed to the institution of slavery, as an ambitious politician he was obliged to avoid any action which might alienate him from the South. Thus he adopted the doctrine of "popular sovereignty," hoping to attract the South without alienating the North. In other words, Douglas tried to have it both ways by taking a stance that would alienate neither side. In the end, that strategy failed him, as the breakup of the Democratic Party in 1860 helped elect Abraham Lincoln.
The repeal of the Compromise of 1820 soon led to the "Appeal of the Independent Democrats":
We arraign this bill as a gross violation of a sacred pledge; as a criminal betrayal of precious rights; as part and parcel of an atrocious plot to exclude from a vast unoccupied region immigrants from the Old World and free laborers from our own States, and convert it into a dreary region of despotism, inhabited by masters and slaves.
"Bleeding Kansas." It has been claimed that the Kansas-Nebraska act was the greatest single step on the road to the Civil War. That claim is borne out by what occurred in Kansas once the act went into effect. Settlers moving into Kansas, especially anti-slavery settlers from the Northeast, were often threatened with violence. Travelers were met at the border by rifle-toting Missourians who suggested that Kansas might not be "safe" territory and strongly urged them to turn around. When word got back to abolitionist leaders in New England, they responded in kind. Pro-abolitionist northerners armed with rifles—"Beecher's Bi-bles"—began to clash with "border ruffians" from Missouri.
Before long a mini-Civil War had broken out, where competing governments, one "legal" and one legitimate, vied for control. John Brown and his followers carried out what became known as the "Pottawatomie Massacre," in which five slave owners were murdered. The Governor received federal troops, but many were killed and much property was destroyed. In Congress Massachusetts Senator Charles Sumner's "Crime Against Kansas" speech led to his being severely beaten by a Southern Congressman, Preston Brooks, on the grounds that Southern honor had been offended. Brooks resigned but was later reelected to Congress. Sumner was incapacitated for months.