Amid high anticipation and sharp criticism, Donald Trump is set to step onstage in Studio 8H tonight to host "Saturday Night Live." Despite a 40-year history of lampooning politicians while inviting some to mock themselves as on-air guests, booking a presidential candidate to host the NBC sketch-comedy show is almost unprecedented. Al Sharpton in 2003 was actively involved in a presidential bid at the time. This time, "SNL" will serve as a campaign stop on Trump's drive for the Republican presidential nomination.