Where are the GOP successes?  Where are their economic or foreign policy successes?
The GOP is great at messaging, and really poor at governing. Small government, low taxes, freedom for citizens sounds really great.  Mommy government and this failure and that failure sounds terrible.  But the GOP cannot actually deliver.  They have not in any state.
The GOP talks a great fight, but the beneficial results are only for the rich and corporations.
The Dem problem is that actual governing is hard, and they try explain those difficulties. People do not want to hear that, no matter how factual it is.  But when the people do elect Dems, the results are much better, as we can see in the states.  Donor Dem states. Taker Red States.
The Dems just do not know how to message it. And they never did. "I do not belong to any organized political party.  I'm a Democrat." (Will Rogers).