The Democratic Party's election results have been a disaster during the Obama years. On all levels, the Republicans have dominated. But before you listen to deep theories specific to this President or the current situation, take a look just a few years ago to 2008:
After Geoorge W Bush dominated politics for 8 years he left office with:
Democrats 29 governorships (had 19 in 2000)
Democrats 59 Senate seats (had 50 in 2000, 44 in 2004)
Same thing happened in the states
Democrats ended the Bush years with full control of
of 23 states snd one part of 13 more up from 17 and 11.
It's clear why this happened in 2008 and now over the past years to Obama. The winning presidential side gets to the business of governing, and compromising to get what they can. The losing side gets to obstruct and criticize with no accountability. At election time it is much easier to run against something real or perceived than to promote a record. Take healthcare, many liberals wanted single payer, and are disappointed with the private sector role in Obamacare. So on one side Obamacare is. attacked as a radical liberal law. On the other side it's not defended vigorously because it's not s radical liberal law.
Disappointed winners lead to lower turnout and enthusiasm and the rise of an opposition which wants to vent anger.
This is healthy in our system. It keeps our politics non-violent and the system working.
Along the way as we go back and forth the losing parties change to pick up and subtract different voters, and eventually the American people get the politics they want.
This is America. I love it!