What groups of people were fighting against manifest destiny and why?

Various groups opposed Manifest Destiny, including Native Americans, Mexicans, and abolitionists. Native Americans fought to protect their lands and sovereignty from encroachment, while Mexicans resisted the loss of their territory following the U.S.-Mexican War. Abolitionists opposed the expansion of slavery into new territories, fearing that Manifest Destiny would exacerbate sectional tensions and entrench the institution of slavery in the United States. These groups highlighted the moral, cultural, and political consequences of America’s westward expansion.