Which group addressed the issue of slavery in the Election of 1848 by opposing slavery in new territories?

Calhoun and "Southern Rights." On the other side of the spectrum, John C. Calhoun staked out a firm "Southern rights" position based on his Senate resolutions. Calhoun articulated in 1848 what secessionists would repeat in 1860: that the Constitution itself protects the right of property and that no law passed by Congress can ever tell a man where he can or cannot take his property.