Comment by hakfoo

The bloviation on manufacturing is cargo-culting. It's a promise of a better time for an electorate that's being squeezed by ever increasing precarity. It's a rose-coloured version of 1950, when people with a high-school diploma could walk into a giant General Motors factory and get a job that paid enough to raise a family, own a house, and retire at 60 with a pension. Obviously, this was based on the US being a dominant manufacturing power.

(They neglect that what made it the dominant manufacturing power was a war that killed tens of millions and sidelined most other industrial nations, but perhaps that's plan B when this doesn't work)

As for using tarriffs to deliver the factories, they assume the US market is so vast and desirable, that it's worth building plants and full supply chains specifically for it. I'd expect that any firm that believed that had onshored their factories years ago due to plain economics, without a comical tarriff regime to spur it. (I'm thinking of how "foreign" automakers sprinkled plants all over the South making models that largely fit US preferences)

Conversely, I suspect you'll see a lot of firms say "we'll just skip the US entirely" -- the factory you built in Viet Nam or Germany can still sell cheaply to a hundred and fifty countries, and together that adds up to more than even the US can offer.