Final answer:
The De Lome letter suggested criticism of President McKinley and support for Cuban rebels, which escalated tensions and influenced American public opinion against Spain.
Step-by-step explanation:
The De Lome letter indicated criticism of U.S. leaders and support for Cuban rebels. This correspondence, sent by Spain's ambassador to the United States, Enrique Dupuy de Lôme, included disparaging remarks about then-President McKinley, labeling him as "weak" and a "bidder for the admiration of the crowd". The letter exacerbated tensions between the United States and Spain and stirred American public opinion, partly contributing to the outbreak of the Spanish-American War.