Former President Barack Obama has publicly backed his ex-vice president even after a “bad debate” night, but behind closed doors, Obama has reportedly expressed concerns that Joe Biden may have hurt his chances of winning re-election. Obama told allies behind closed doors who reached out to him that Biden’s path to re-election became a tougher challenge following the debate against former President Donald Trump, The Washington Post reported Tuesday night. The two reportedly talked over the phone following the disastrous night that left many openly questioning Biden’s cognitive health and some …