Final answer:
The Republican Party was founded largely in opposition to the expansion of slavery.
Step-by-step explanation:
The Republican Party was founded in 1854 largely in opposition to the expansion of slavery. The passage of the Kansas-Nebraska Act, which allowed territories to decide for themselves whether or not to allow slavery, was a key catalyst for the creation of the party. The Republican Party opposed the spread of slavery into new states and territories, embodying a more progressive and abolitionist stance compared to the Democratic Party at the time.
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