Final answer:
The Free-Soil Party was formed as a response to the contentious debate over the expansion of slavery into new territories, particularly following the Wilmot Proviso. This new party opposed the notion of spreading slavery, driven by concerns over free labor and fear of a Slave Power conspiracy, leading to a significant impact on American politics as shown through their congressional representation.
Step-by-step explanation:
The formation of the Free-Soil Party was precipitated by the deepening sectional and political divisions in the United States leading up to the election of 1848. Opposition to the expansion of slavery was a pivotal factor in the creation of this party. Key events such as the proposal of the Wilmot Proviso, which sought to ban slavery in any territory acquired from Mexico, highlighted the contentious debate over whether new territories should permit slavery. This debate was central to the Free Soilers' platform.
The diverse coalition that formed the Free-Soil Party included antislavery Whigs, Democrats disillusioned with their party’s stance on slavery, and former members of the Liberty Party. The party demonstrated significant political influence, winning seats in both the House and Senate, and contributing to the evolving political landscape as tensions over slavery intensified.
The events leading up the Compromise of 1850 and the subsequent drift toward secession further exacerbated these divisions. The Republican Party, formed later in 1854, continued to challenge the expansion of slavery, leading to increased Southern fears and discussions of secession, setting the stage for the Civil War.