An eloquent, comprehensive examination of that question is found in the book “American Psychosis: A Historical Evaluation of How the Republican Party Went Crazy,” by David Corn. Check out these reviews:
The Republican Party’s downward spiral hit high gear when it nominated for President an immoral reprobate caught bragging about sexually assaulting women. Who then proceeded to mock the handicapped, demean the military service of John McCain, be found guilty of sexual assault. Want to do all the above and get elected to office? Run on the Republican ticket.