Alan Keyes is a conservative speaker and activist who has run for President and the Senate numerous times (always losing, thankfully – in 2008 he ran with Wiley Drake). He is most famous for being clinically insane, completely ignorant and pathologically intellectually dishonest. More about his career can be found here and here. He used to try to run on a Republican ticket, but after 2008 ran with the Constitution part - but since they supported Chuck Baldwin he started his own party, the Independence Party.
He is insanely anti-gay, actually arguing that gay people cannot have sex (they are rather “mutual pursuit of pleasure through the stimulation of the organs intended for procreation, but it has nothing to do with sexuality because they are of the same sex. And with respect to them, the sexual difference does not exist. They are therefore not having sexual relations”). When Keyes’s own daughter came out as homosexual, she was promptly disowned.
He is a strong champion of gun rights, coming up with reassuring claims such as “gun owners are pro life and their guns are to defend the lives of the unborn” (see also this). He has also claimed that downturns in the economy prove that God is angry with legalized abortion.
Keyes is also a staunch supporter of teaching Biblical creationism in public schools, and he supports mandatory prayer and faith initiatives – as long as they are not Jewish, since Jewish (as opposed to Christian) initiatives promote enmity and hatred (see also this). He is also a firm believer in theocracy and the religious foundation of the U.S. - in the sense of Gary Bauer, Gary DeMar, Gary North and David Barton (who should apparently change his name to “Gary” as well). See also this.
In November 2008 Keyes (and Markham Robinson) filed a lawsuit against the California Secretary of State, then-President-elect Barack Obama, then-Vice President-elect Joe Biden, and California's 55 Democratic electors, seeking to challenge Obama's eligibility for the US Presidency (though Keyes didn’t like McCain either). The suit requests that Obama provide documentation that he is a natural born citizen of the United States. Following Obama's inauguration, Keyes denied he had been constitutionally inaugurated, refused to call him President, and called him a "usurper" and a "radical communist". He has even resorted to civil disobedience over the matter (though refusing to call it “civil disobedience, since he doesn’t believe in that). Keyes is thus one of the most central idiots of the birther movement. He has also been affiliated with the Christian Exodus independence movement.
Keyes also made a rather unflattering appearance in Borat.
Diagnosis: Blatheringly moronic fundamentalist and rabid clown. He has some die-hard followers, but even the more extreme Republican wingnuts often find that they have to distance themselves from him.