Final answer:
The increasing sectional tension over slavery and nativism in the 1850s led to the decline of the Whig Party and the rise of new political entities, most notably the Republican Party. These new parties emerged from the turmoil created by issues like the Kansas-Nebraska Act and the subsequent violence in Kansas, also known as 'Bleeding Kansas.' This period marked a significant realignment in American politics.
Step-by-step explanation:
The Collapse of the Second Party System and Rise of New Parties
Sectional issues surrounding the expansion of slavery and the influence of immigrants played pivotal roles in reshaping American politics during the 1850s. The Whig Party, weakened by internal divisions on these issues, saw their influence decline, particularly after the Kansas-Nebraska Act, which divided Democrats and further fractured the Whigs. This political turbulence helped pave the way for the emergence of the Republican Party, formed by anti-slavery Whigs, Democrats, and members of the Free-Soil Party. The ongoing strife in Kansas, known as 'Bleeding Kansas,' exemplified the deepening sectional divides and portended the breakdown of the Whigs and the rise of the Republican Party as an antislavery force, which eventually supplanted the Whig Party after the violence in Kansas and the attack on Senator Charles Sumner in the Capitol by Representative Preston Brooks.
As the Democratic Party continued to push for territorial expansion, this often involved the contentious issue of spreading slavery into new territories. In contrast, the Know-Nothing Party, or the American Party, capitalized on nativist sentiments, focusing primarily on concerns about immigration. The complex interplay of these dynamics contributed to the realignment of political parties in the United States, with the sectional conflict over slavery and nativism ultimately undermining the existing two-party system and setting the stage for the rise of the Republican Party as a prominent political force.