Polk's use of a 'spot resolution' refers to a specific request made by Congressman Abraham Lincoln in 1847, demanding that President James K. Polk identify the exact location where American blood was shed on American soil, which justified the declaration of war against Mexico. This resolution challenged the legitimacy of Polk's claim that American forces had been attacked on U.S. territory, highlighting the contentious debate over the Mexican-American War and the role of expansionist policies in U.S. politics.