Answer:
One of his campaign promises during the 1844 election was to annex the Republic of Texas into the United States. Polk ran on a platform of manifest destiny and expansion, advocating for the annexation of Texas, the reoccupation of Oregon Country, and the acquisition of California from Mexico. He fulfilled these promises during his presidency, resulting in the annexation of Texas and the Oregon Treaty of 1846, which settled the boundary dispute with Britain. His administration also played a role in the lead-up to the Mexican-American War, which ultimately led to the acquisition of California and other southwestern territories.