What characterized the Republican Party formed in the 1850s?

The Republican Party, founded in the 1850s, was primarily characterized by its staunch anti-slavery platform. This emerging political party was formed in response to the expanding influence of slavery in the United States, particularly following events such as the Kansas-Nebraska Act, which allowed for the possibility of slavery in territories where it previously had been prohibited.

The party attracted a diverse coalition of former Whigs, Free Soilers, and anti-slavery Democrats, all united by a common goal: to prevent the extension of slavery into the western territories. This focus on opposition to slavery was a defining feature of the party's identity and significantly influenced its policies and electoral strategies in the years leading up to the Civil War.

The other options do not accurately reflect the central tenets of the Republican Party during this formative period. The party's explicit opposition to slavery was crucial in distinguishing it from others and helped secure its position as a leading political force during a critical time in American history.