But these are only very recent developments. Barack Obama and Hillary Clinton may be champions of same-sex marriage now, but you don’t have to go far back to find a time when they weren’t. And hey, we’re happy to have their evolved support.
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Not only did Sanders vote against the Defense of Marriage Act in 1996 which defined marriage as between one man and one woman, signed into law by then-president Bill Clinton — an unpopular position then — a look back at Sanders’ political career shows consistent support of the gay rights movement. Even when it was more than just unpopular, it was downright controversial.
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But Sanders was unfazed. The following year he signed a resolution recommending that all levels of government support gay rights, and the year after that in 1985 (the same year then-president Reagan finally said the word ‘AIDS’ in public), he wrote:

“It is my very strong view that a society which proclaims human freedom as its goal, as the United States does, must work unceasingly to end discrimination against all people. I am happy to say that this past year, in Burlington, we have made some important progress by adopting an ordinance which prohibits discrimination in housing. This law will give legal protection not only to welfare recipients, and families with children, the elderly and the handicapped — but to the gay community as well.”

http://www.queerty.com/32-years-before-marriage-equality-bernie-sanders-fought-for-gay-rights-20150719