On January 19, 2004, Dean's rivals John Kerry and John Edwards pushed him into a third-place finish in the 2004 Iowa Democratic caucuses, representing the first votes cast in primary season. Dean's loud outburst in his public address that night was widely rebroadcast and portrayed as a media gaffe that ended his campaign.
Today a candidate can advocate for turning homeless people into paste and that doesn't sink them but back in 2004 this gaffe did him in. It's great how tolerant we've become as a society!