The central role of the president’s overall approval rating in deciding his reelection fate underscores the conundrum that Trump so vividly demonstrated this week. Across a wide array of public and private polls, he’s not consolidating nearly as much support as previous presidents with voters satisfied with the economy, many of them financially comfortable, suburban, and college-educated. (Those were the same voters who turbo-charged the Democratic sweep of affluent metropolitan-area congressional districts last November.) The CNN and ABC/Washington Post polls show Biden winning just under one-fifth of voters who say they approve of Trump’s economic performance, a much higher level of defection than Bush or Obama suffered among the economically satisfied.

By all evidence, those defections are driven at least partly by the divisive confrontations Trump constantly stirs over race, gender, and culture. And yet Trump feels compelled to keep fueling those fights, as he repeatedly did this week, in part because the fires he has already lit may have permanently repelled too many of the voters satisfied with his economic record. He has to double down on stirring turnout from his base through racial and cultural strife to offset his underperformance with swing voters alienated by exactly that behavior. It is as if Trump is on two diverging roads: He has already moved so far down the path of centering 2020 on American identity that he can no longer realistically cross back to focusing it primarily on the economy. He fights over American identity not only because he likes to, but because, by this point, he must.