True or False The newly formed Free - Soil Party, whose members were mostly southerners, campaigned for popular sovereignty in the western territories.

This is False, the free-Soil Party were not campaigning for popular sovereignty.

Explanation:

The free-soil party was a single - issue party with a aim to end the practice of slavery in the newly established, western territories of the United States.

The party was officially active for only 6 years between 1848 to 1854, however, they were able to muster huge support in New England but this did not pose any significant threat to the most established political parties.

It eventually dissolved with most members becoming part of the Republican Party.