We'll be able to measure how much support for something like that he can get. Also, we can easily see Canada and Mexico retaliating against American goods with similar tariffs.
In any case, this is meant to stir up his supporters. If the Legislative blocks him, he still wins by becoming the victim of a "legislative power grab".
If this winds up going through, people all over the country are going to see the sticker shock at the store very quickly.
I have hope for the Senate. They weren't going to confirm Gaetz. Yeah, there are a bunch of other things they need to not go along with, but they aren't going to be complete doormats.
https://constitution.congress.gov/browse/essay/artII-S2-C2-1...
If nothing else, the President can unilaterally declare that the other country is in breach of the treaty, so it's no longer in effect.