Truth is what the Party says is truth. Think of the novel 1984, where the Inner Party member, O’Brien, waved four fingers in front of Winston Smith and asked him how many fingers he saw. Smith was beaten and tortured when he asserted that he saw four fingers until he was broken and told O’Brien that it depended on what O’Brien said it was.
I think the Democrats believe that if they tell a lie often enough everyone will believe it is the truth or in today’s lingo ... the new norm.