Nobody is demanding a 2000 mile wall. Not that these people care about facts.
Losing the House was largely based on repeated lies from Dems. They campaigned on the fear that Republicans would take away their health care, take away protection for pre-existing conditions (which Trump campaigned against in every rally), would take away their social security and wanted to build a 2000 mile long wall, which Trump has never advocated. People on the left heard these things over and over and voter for Dems.