I follow politics closely. I have for probably 30 years. A common rightwing propaganda tactic is to accuse their enemies of doing that which they themselves are guilty of doing.
So if a Republican president says some horrific racist stuff, like calling African countries “shitholes,” the response could be to say that it’s actually Democrats who are the racists.
It’s an old tactic of the fascist.
In 1934, Nazi propagandist Joseph Goebbels spoke about it in Nuremberg.
The cleverest trick used in propaganda against Germany during the war was to accuse Germany of what our enemies themselves were doing.
Goebbels was talking about attacks against Germany, but the Nazis used this propaganda trick often.
The effect of this technique is that even though not everyone will believe that Democrats are racists too, this tactic leaves the general sense that both sides are doing it and no one can really be trusted.
This bolsters this notion that everyone is lying and everyone is engaged in political shenanigans and all politicians are crooks. It gives those people actually engaged in bad behavior room to operate. And it turns off millions of voters who might not vote Republican.
I don’t know why liberals don’t do it. I’m guessing because it’s just too intellectually dishonest.