Which single-issue party worked to stop the speard of slavery?

The single-issue party that emerged in the United States to combat the spread of slavery was the Liberty Party, founded in 1840. Its primary goal was to advocate for the abolition of slavery and to promote the rights of African Americans. The party played a crucial role in bringing the issue of slavery to the political forefront, influencing later parties and movements that aimed to end the institution. Ultimately, the Liberty Party laid the groundwork for the formation of the Republican Party in the 1850s, which took a stronger stance against slavery's expansion.