As the media spreads more lies, the truth will come back to them in the end because they are each responsible for the untruths they print to the population. No one gets away with deliberate manipulations. With power, comes responsibility; from a much higher authority will judge them.
Cantor lost because he diverged so far from his party’s platform (and got so out of touch with his district) that a political unknown could beat him simply by running on the party platform.
Amnesty is probably the most significant, but I imagine spending/debt and failure to serious address Obamacare added up to.