A resolution condemning the alt-right and white nationalism has split the annual gathering.
Alt-right figurehead Richard Spencer held a torchlit rally to protest the removal of a memorial to Confederate Army leader Robert E. Lee.
Trump is expected to pick Andrew Puzder as labor secretary.
Clinton's accusations came as Trump tried to soften his image and appeal to minorities.
Scalise admits it, but three attendees have claimed that he did not speak at the event.