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President Trump’s critics and admirers have both often wondered whether most of the normal rules of politics apply to him. Trump, in his own graphic way, may have summarized the view best: “I could stand in the middle of Fifth Avenue and shoot somebody, and I wouldn’t lose any voters, O.K.?”

But it turns out that the normal rules of politics do indeed apply to Trump.

With his approval rating at a paltry 38 percent, Trump’s Republican Party took a whupping. It’s not just that the Democrats easily won the highest-profile race — the Virginia governorship. Democrats enjoyed a stunningly good night across the country. Consider:

• Defying virtually all expectations, Democrats flipped more than a dozen of the 100 seats in Virginia’s house of delegates and, pending final vote counts, may have won control of it.

• They won full control — legislature and governorship — in both New Jersey and Washington State.

• Maine’s Republican governor has repeatedly vetoed Medicaid expansion. Maine’s voters effectively overrode his veto, by referendum, in a landslide.