Final answer:
James Polk, during his 1844 presidential campaign, supported Manifest Destiny, which was the belief that the United States was destined to expand across the North American continent.
Step-by-step explanation:
During his 1844 presidential campaign, James Polk pledged his support for Manifest Destiny. Manifest Destiny was the 19th-century doctrine that the expansion of the United States throughout the American continents was both justified and inevitable. This belief drove the U.S. policy and action, resulting in the annexation of territory, such as Texas and Oregon.
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