Mike Murphy (political consultant) quotes
[H]ow popular is the president? Normally, they lose seats when they are kind of average popular. If they are unpopular, it tends to have a magnifying effect. And we do know, from averaging all the polls together, that Donald Trump is the most unpopular first-year president in the history of polling, easily. There's nobody – he is first, second, and third place. So that is a bad thing... You know, there could be a foreign intervening event. Martians land with the same hair and say, you know, "Only he understands us, and we are going to save the planet." But, assuming normalcy, the forces are pretty bad.
Mike Murphy (political consultant)