Ron Brownstein: “Extraordinarily narrow and unstable House and Senate majorities have become routine in modern American politics. The frantic, final maneuvering last week before Congress approved President Donald Trump’s One Big Beautiful Bill Act shows why that’s likely to persist for some time.”“And that means business, local governments, non-profits and ordinary Americans need to buckle up for more hairpin turns in national policy that make it almost impossible to plan for the long term.”