Herschel Walker’s 100,000-vote loss in Georgia puts the exclamation point on the “Donald Trump is electoral poison” narrative. If the former president had deliberately attempted to sabotage the Republicans' chances ever since November 2020, he could not have been more destructive than he actually was. In the Senate, the Trump effect meant Republicans lost chances at a whopping 10 seats (one of them two times!) they either should have won or in which they might have been competitive. In the House, Trump’s harm was more diffused, but almost equally baleful. On Jan. 5, 2021, Republicans lost two Senate seats in...