Current and former White House staffers who spoke to Axios this week say Trump really does believe that tariffs are paid for by foreigners. It's "like theology," they say.
Farm state Senator Chuck Grassley (R-IA), on the other hand, says Trump doesn't really believe the things that come out of his mouth.
Grassley on Trump: “He believes in tariffs as a tool to get a negotiation as opposed to being an end in themselves. Then he hasn't changed anything. If he has used tariffs because he believes they're good, and I know he says that, but I don't believe he actually believes that. I don't see how he could believe it.”
“[H]e hasn't changed the Republican Party. We're still a party of free trade … I surely hope that he has learned from history that lower tariffs are good.”
I imagine that farmers in Grassley's home state of Iowa don't necessarily care if Trump really believes the things that he says because the effect is the same either way. Trump is destroying American agriculture whether he truly believes in tariffs or not.
I don't think Grassley or any other Republican can credibly claim that the Republican party is still a "party of free trade" because, if they were, they would stop Trump's trade war. Senate Republicans could stop Trump tomorrow if they really wanted to, but they don't and they won't. They've barely even criticized Trump's tariffs.
Republican opposition to free trade actually began while President Obama was still in office. Congressional Republicans killed the Export-Import Bank which facilitated trade in developing markets and they opposed the Trans-Pacific Partnership on rhetorical grounds.
Members of both parties have said things about trade that aren't true and Trump's trade war is the consequence of that.