1) Reinforces that the target is the leader - or else the attn wouldn’t be necessary
2) Digs in that candidate’s supporters and actually reduces their openness to negatives
Oppo is a “category sale”. It says “someone else would be better” but does very little to lift up any specific “someone else” while entrenching some rigid support for the target.
Dump the whole shaker though and people won’t be all that excited about the chef.