How did the Republican Party change? What does Trump believe that are not in line with the Republican Party ideology?
The ONLY major difference between Trump and previous milk toast Republicans is he can afford to take on the DC deep state. We need more like him.
In the past, the Republicans were in favor of free trade without considering whether the trading partner actually was equally open to our products. This was a problem that both parties had.
Trump is the first president to really push for "reciprocal" trade. In other words, he uses tariffs and other tools as leverage to force a trading partner (like China) to open up more of their markets to our products.