Anybody remember Ben Nighthorse Campbell, first elected as a Democrat U.S. Senator from Colorado in 1992? A full-blooded Cherokee.
In 1995, tired of the lies and duplicities of the Democrat party, he switched to Republican and remained so to the end of his career.
Also, there was Charles Curtis, a full-blood who became the first--and thus far only--Native American vice-president, under Herbert Hoover in 1928. Republican.