Most frequently, this goal is accomplished by labeling opponents with emotionally-freighted terminology (racist/sexist/bigot) that immediately serves to put its objects on the defensive while distracting from their own contrary arguments.
Republicans have only rarely figured out how to defeat such techniques, either because they allow themselves to be intimidated, or lack understanding of the principles they are supposed to defend, or simply lack principles.
In other words, leftists never argue based on the merits of the issues and concerns being raised, because they can’t.
Instead they attack their opponents as illegitimate, intellectually/morally inferior, or, in the case of their prototype communist template country, USSR, classify opposition as “insane”.