"and I congratulate the Democrat majority."
Remember this is an example of the exactitude and detail some speeches merit. This one phrase was commented on extensively and noted as an insult and a slam and a jab. And this offers
some in-kind names such as "Republicant".
But all this is a digression of function over form.
It was a grammatical blunder - which is simply poor form. "Democrat" is a noun, "Democratic" is an adjective.
If the president gets raked over the coals for it, do you expect to escape in any better shape?