Final answer:
President McKinley proposed to Spain that it end harmful policies in Cuba and declare Cuban independence to avoid war. Spain's response did not guarantee Cuban independence, leading to the U.S. Congress authorizing war and adopting the Teller Amendment, which eventually resulted in Spain severing diplomatic ties and declaring war.
Step-by-step explanation:
To avoid a war with Spain, President McKinley offered several concessions. In late March, he proposed that Spain end its policy of reconcentración, which concentrated the population of Cuba into military camps, and pushed Spain to declare Cuba's independence. Spain provided relief to the Cuban people, ended the reconcentración camp policy, and agreed to an armistice with Cuban rebels. However, Spain made no guarantees regarding Cuban independence, which led McKinley to ask Congress for authorization to use military force. Consequently, Congress passed a joint resolution on April 19, 1898, that recognized Cuban independence and authorized military intervention, along with the Teller Amendment that stipulated the United States would not annex Cuba. In response to the U.S. actions, including a naval blockade of Cuba, Spain severed diplomatic ties and declared war on April 24, which the United States reciprocated, officially entering the Spanish-American War.