The democrats,one would have majorly politicized it.
Two, Republicans lost because they were lazy, corrupt, often hateful...and there was more often than not more gridlock with a Republican majority than without.
Completely in charge of 3 branches of government and can't even get a damn bill passed.
They weren't coming together on even the most basic of principles such as taxes.
The ones on the waaaay right end of things... to them if things weren't 100% all the way over on their end of the spectrum they would say 'no way'.
They could have moved the whole country to the right a whole lot more by giving in just a little here or just a little there in a manner of compromise. Head butting Republicans cost us a whole lot of opportunity.
But hell no. They wanted it all and wanted it all to be theirs right now.
On top of that they began to believe their butts were glued to a congressional seat and that they were just owed the position.
All in all they had it coming.