Complex sentence: Trump's disdain for what he considers to be political correctness has been a staple theme of his campaign and has proved to be popular among his supporters, although mainstream commentators and some prominent Republicans have viewed him as appealing explicitly to racism.
Split into simpler sentences: Trump's disdain for what he considers to be political correctness has been a staple theme of his campaign. Mainstream commentators and some prominent Republicans have viewed him as appealing explicitly to racism.