It's not a new phenomenon - it only seems so because the media has no historical perspective. There was a furious minority that hated FDR with a passion. Lincoln inspired visceral hatred. Thomas Jefferson did as well. Andrew Jackson was absolutely despised by his political opponents, who spared no expense in the media of the day to make that fact known.
The only difference is that we have the internet and 24x7 media now to let us find like-minded individuals anytime we want. The level of visceral dislike though - not new at all