as far as president McKinley was concerned. there was a government in operation in Hawaii that was recognized by all the major powers.  The old Queen had been overthrown and no one paid her attention. It was threatened by a possible takeover from japan. It strongly wanted annexation to the US (for military protection and for access to the US sugar market) The Democrats strongly opposed annexation of Hawaii (and the Philippines) because they did not want Asiatics. The Republicans were much more liberal on race and wanted an empire, hence bases in Hawaii. The Democrats blocked a treaty (needed 2/3 vote) so the Republicans voted annexation by resolution (50% vote), just as texas had been annexed by resolution in 1845.  They offered citizenship to all citizens of Hawaii (most of them non-white) and set up elections. The heir to the old throne Prince Kuhio  was elected as a Republican to Congress in 1902.