[158] The United States acquired Puerto Rico and the Philippines as well as the island of Guam, and Spain relinquished its claims to Cuba; in exchange, the United States agreed to pay Spain $20 million (equivalent to $651 million in 2021).[158] McKinley had difficulty convincing the Senate to approve the treaty by the requisite two-thirds vote, but his lobbying, and that of Vice President Hobart, eventually saw success, as the Senate voted in favor on February 6, 1899, 57 to 27.[159]

Hawaii
Annexation of the Republic of Hawaii in 1898
During the war, McKinley also pursued the annexation of the Republic of Hawaii. The new republic, dominated by business interests, had overthrown the Queen in 1893 when she rejected a limited role for herself.[160] There was strong American support for annexation, and the need for Pacific bases in wartime became clear after the Battle of Manila.[161] McKinley came to office as a supporter of annexation, and lobbied Congress to act, warning that to do nothing would invite a royalist counter-revolution or a Japanese takeover.