Before this, the only person he ever challenged was Bernie- and in that case, his viciously condescending attacks on Bernie for even daring to run for president at all-despite the fact that Hillary was doomed to lose the whole time due to her unwillingness to offer any meaningful program for change or any willingness to fight for economic justice and the needs of working-class voters- was completely unjustified and inappropriate. Bernie did nothing to deserve that and it was solely Hillary's fault that Trump carried the firewall states in '16.