He was called a racist many times before, including all the times he was sued for illegal racial discrimination (the first of which was more than 40 years ago.)

Now, maybe that hasn't gotten a lot of media player in places that you would notice while those in the Presidential campaign did, but that says more about your personal media consumption than anything else.

First I ever heard of his political views was when he ran for President.

If he'd been open and up-front about those views, I'm sure they would have been opposed, had anyone bothered to take him seriously. Though more likely he would have just been written off as some rich crank, much as he was at the start of his campaign.

The serious political opposition to him really mounted as his chances at getting political power increased. That, combined with people starting to realize what he and his biggest fans (Neo-Nazis and other white nationalists) stood for was why he's been called a racist now as opposed to when he was just another business man with his politics in the closet.

This is ignorant of his history: http://nytimes.com/2002/10/23/nyregion/trump-draws-criticism...

Things change when you enter the political arena, particularly run for president. Regardless of your political stripes or those of your opponent.