Everyone knows the Trump-Biden election campaign is going to be nasty, brutish and not short enough, but the unknown is how much policy damage it will do. One unfolding example is the fiasco of self-destructive opposition to 

Nippon Steel’s proposed acquisition of U.S. Steel.

The American political consensus used to be that foreign investment is a sign of U.S. economic strength and a source of good-paying jobs. Protectionists focused on blocking imported goods that compete with American products. But now they’re targeting even investment in U.S. manufacturing from friendly countries.

That’s the case with Nippon Steel’s non-hostile $14.1 billion offer to buy U.S. Steel, a venerable American name that has fallen well down the ranks of world producers. Nippon Steel executives plan a major capital infusion to make U.S. Steel more productive. But the merger is opposed by 

Cleveland-Cliffs, a U.S. Steel competitor, and the United Steelworkers, and the politicians are following like sheep.